F Teacher Student Book SERIES Name _____________________________________ Multiplication and Division Series F – Multiplication and Division Contents Topic 1 –1 Mental Section – Answers multiplication (pp. 1–32) strategies (pp. 1–10) Date completed • mental doublingmultiplication strategy_______________________________________ strategies__________________________ 1 / / • mental 100s and 1 000s__________________________ 11 / multiplydivision by 10s,strategies______________________________ / • split written strategy__________________________________________ methods_____________________________________ 20 / / • compensation puzzles and investigations______________________________ strategy__________________________________ 29 / / • factors and multiples____________________________________ / / • multiplication facts___________________________________ 33 / use multiplication facts__________________________________ / • mental multiplication strategies_________________________ 37 / divide by 10s, 100s and 1 000s____________________________ / • halving strategies______________________________ 41 / mental division strategy________________________________________ / methods_____________________________________ 43 / written • split strategy__________________________________________ / • tests of divisibility______________________________________ / / • contracted multiplication________________________________ / / • extended multiplication__________________________________ / / • short division__________________________________________ / / • short division with remainders____________________________ / / • solving problems_______________________________________ / / • crack the code – apply___________________________________ / / • smart buttons – apply___________________________________ / / • bugs – investigate______________________________________ / / • puzzles – apply_________________________________________ / / Section – Assessment answers (pp. 33–44) Topic 2 –2 Mental divisionwith strategies (pp. 11–19) Section – Outcomes (pp. 45–46) Topic 3 –3 Written methods (pp. 20–28) Topic 4 – Puzzles and investigations (pp. 29–32) Series Authors: Rachel Flenley Nicola Herringer Copyright © Mental multiplication strategies – doubling strategy Doubling is a useful strategy to use when multiplying. To multiply a number by four, double it twice. To multiply a number by eight, double it three times. 15 × 4 double once = 30 13 × 8 double once = 26 double twice = 60 double twice = 52 double three times = 104 1 Warm up with some doubling practice: a b 2 6 10 1 3 2 3 40 20 4 6 D 5 4 2 c 8 12 9 7 18 30 50 14 10 20 15 25 30 D 70 60 18 40 35 50 24 12 80 192 100 6 9 96 12 24 D 8 32 16 48 16 32 64 Finish the doubling patterns: a4 8 __________ 16 ___________ 32 __________ 64 ___________ 128 __________ b3 6 __________ 12 ___________ 24 __________ 48 ___________ 96 __________ c 5 10 __________ 20 ___________ 40 __________ 80 ___________ 160 __________ d 25 50 __________ 100 ___________ 200 __________ 400 ___________ 800 __________ e7 14 __________ 28 ___________ 56 __________ 112 ___________ 224 __________ f 75 150 __________ 300 ___________ 600 __________ 1 200 ___________ 2 400 __________ Choose a number and create your own doubling pattern. How high can you go? What patterns can you see within your pattern? Answers will vary. 4 Two sets of twins turn 12. They decide to have a joint birthday party with 1 giant cake but they all want their own candles. How many candles will they need? 4 × 12 = 48 Multiplication and Division Copyright © 3P Learning F 1 SERIES TOPIC 1 Mental multiplication strategies – doubling strategy 5 6 7 8 Use the doubling strategy to solve these: To multiply by 4, double twice. To multiply by 8, double three times. ×2 ×4 a13 × 4 26 ___________ 52 ___________ b 16 × 4 32 ___________ 64 ___________ c24 × 4 48 ___________ 96 ___________ d 25 × 4 50 ___________ 100 ___________ e32 × 4 64 ___________ 128 ___________ f21 × 4 42 ___________ 84 ___________ g 35 × 4 70 ___________ 140 ___________ Use the doubling strategy to solve these: ×2 ×4 ×8 a 12 × 8 24 _____________ 48 ____________ 96 ____________ b 14 × 8 28 _____________ 56 ____________ 112 ____________ c 25 × 8 50 _____________ 100 ____________ 200 ____________ d 21 × 8 42 _____________ 84 ____________ 168 ____________ e 13 × 8 26 _____________ 52 ____________ 104 ____________ f 16 × 8 32 _____________ 64 ____________ 128 ____________ Work out the answers in your head using the appropriate doubling strategy. Use a table like the one above if it helps. a 18 × 4 = 72 b 16 × 4 = 64 c 26 × 4 = 104 d 24 × 8 = 192 e 15 × 8 = 120 f 22 × 8 = 176 Nick’s dad offered him two methods of payment for helping with a 5 week landscaping project. Method 1: $24 a week for 5 weeks. Method 2: $8 for the first week, then double the payment each week. Which method would earn Nick the most money? Why? 2 F 1 SERIES TOPIC Method 1 = $120 24 x 5 = 120 Method 2 = $248 8 + 16 + 32 + 64 + 128 = 248 Multiplication and Division Copyright © 3P Learning Mental multiplication strategies – multiply by 10s, 100s and 1 000s When we multiply by 10 we move the number one place value to the left. When we multiply by 100 we move the number two place values to the left. When we multiply by 1 000 we move the number three place values to the left. Look at how this works with the number 45: Ten Thousands Thousands c T Th 4 5 0 4 5 0 0 5 0 0 0 T U 1 7 1 7 0 × 10 1 7 0 0 × 100 1 7 0 0 0 × 1 000 T Th Th H T U 8 5 8 5 0 × 10 8 5 0 0 × 100 5 0 0 0 × 1 000 8 Th × 10 × 100 × 1 000 H b d T Th T U 4 3 4 3 0 × 10 4 3 0 0 × 100 4 3 0 0 0 × 1 000 T Th Th H T U 9 9 9 9 0 × 10 9 9 0 0 × 100 9 0 0 0 × 1 000 9 Th H Try these: a 14 × 10 = 140 b 14 × 100 = 1 400 c 14 × 1 000= 14 000 d 92 × 10 = 920 e 92 × 1 000= 92 000 f 92 × 100 = 9 200 11 000 h 11 × 100 = 1 100 g 11 × 1 000= 3 Units Multiply the following numbers by 10, 100 and 1 000: a 2 Tens 4 5 4 1 Hundreds i 11 × 10 = 110 You’ll need a partner and a calculator for this activity. Take turns giving each other problems such as �Show me 100 × 678�. The person whose turn it is to solve the problem, writes down their prediction and you both check it on the calculator. 10 points for each correct answer, and the first person to 50 points wins. Answers will vary. Multiplication and Division Copyright © 3P Learning F 1 SERIES TOPIC 3 Mental multiplication strategies – multiply by 10s, 100s and 1 000s It is also handy to know how to multiply multiples of 10 such as 20 or 200 in our heads. 4 × 2 helps us work out 4 × 20: 4 × 2 = 8 We can express this as 4 × 2 × 10 = 80 4 5 4 × 20 = 80 How would you work out 4 × 200? Use patterns to help you solve these: 10 a 5 × 2 _____________ 5 × 20 100 _____________ 5 × 200 1000 ___________ 18 b 2 × 9 _____________ 2 × 90 180 _____________ 2 × 900 1800 ___________ $24 c 6 × $4 _____________ $240 6 × $40 _____________ 24 d 8 × 3 _____________ 8 × 30 $21 e 3 × $7 _____________ $210 3 × $70 _____________ 16 f 2 × 8 _____________ 20 × 8 160 _____________ 200 × 8 1 600 ___________ 27 g 3 × 9 _____________ 30 × 9 270 _____________ 300 × 9 2 700 ___________ 240 _____________ $2 400 6 × $400 ___________ 8 × 300 2 400 ___________ $2 100 3 × $700 ___________ Answer these problems: a Jock runs 50 km per week. How far does he run over 10 weeks? 500 km If you’re struggling with your tables, get onto Live Mathletics and practise! bHuy earns $20 pocket money per week. If he saves half of this, how much will he have saved at the end of 8 weeks? $80 cThe sum of two numbers is 28. When you multiply them together, the answer is 160. What are the numbers? 20, 8 6 4 Finish these counting patterns: a 10 20 30 __________ 40 __________ 50 ___________ 60 __________ b 20 40 60 __________ 80 __________ 100 ___________ 120 __________ c 30 60 90 __________ 120 __________ 150 ___________ 180 __________ d 40 80 120 __________ 160 __________ 200 ___________ 240 __________ e 50 100 150 __________ 200 __________ 250 ___________ 300 __________ f 100 200 300 __________ 400 __________ 500 ___________ 600 __________ g 200 400 600 __________ 800 __________ 1 000 ___________ 1 200 __________ F 1 SERIES TOPIC Multiplication and Division Copyright © 3P Learning Mental multiplication strategies – split strategy Sometimes it’s easier to split a number into parts and work with the parts separately. Look at 64 × 8 Split the number into 60 and 4 Work out (60 × 8) and then (4 × 8) Add the answers together 480 + 32 = 512 1 Use the split strategy to answer the questions: a 46 × 4 b 74 × 5 (40 × 4) + (6 × 4) 5 4 × ___) 5 + (___ 70 × ___) (___ 4 8 × ___) 4 + (___ 40 × ___) (___ 24 160 + _______ _______ 20 350 + _______ _______ 160 + _______ 32 _______ = = = 184 d 37 × 7 2 3 c 48 × 4 370 e 62 × 8 192 f 91 × 5 7 7 × ___) 7 + (___ 30 × ___) (___ 8 2 × ___) 60 × ___) 8 + (___ (___ 5 1 × ___) 5 + (___ 90 × ___) (___ 49 210 + _______ _______ 480 + _______ 16 _______ 450 + _______ 5 _______ = = = 259 496 455 Use the split strategy to answer the questions. This time see if you can do the brackets in your head: 64 320 + __________ = a 48 × 8 = __________ 384 14 350 b 52 × 7 = __________ + __________ = 364 360 27 c 9 × 43 = __________ + __________ = 387 160 72 d 8 × 29 = __________ + __________ = 232 42 560 e 86 × 7 = __________ + __________ = 602 It's a good thing I know how to work with multiples of ten in my head! These problems have been worked out incorrectly. Circle where it all went wrong. a 37 × 6 b 17 × 5 c 32 × 9 (30 × 6 ) + (7 × 6) (10 × 5) + (7 × 5) (30 × 9) + (2 × 9) 180 + 13 70 + 35 27 + 18 = 193 = 105 = Multiplication and Division Copyright © 3P Learning 45 F 1 SERIES TOPIC 5 Mental multiplication strategies – split strategy 4 Each trail contains 2 multiplication problems and steps to solve them. Only one trail has been solved correctly. There are errors in the other two. Find and colour the winning trail. FINISH 78 291 114 (30 × 9) + (3 × 9) (10 × 6) + (3 × 6) 13 × 6 464 (40 × 7) + (2 × 7) 42 × 7 (10 × 9) + (6 × 9) 33 × 9 294 16 × 9 51 400 + 64 58 × 8 30 + 21 17 × 3 START The middle path is correct. 6 F 1 SERIES TOPIC Multiplication and Division Copyright © 3P Learning Mental multiplication strategies – compensation strategy When multiplying we can round to an easier number and then adjust. Look how we do this with 4 × 29 29 is close to 30. We can do 4 × 30 in our heads because we know 4 × 3 = 12 4 × 30 = 120 We have to take off 4 because we used one group of 4 too many: 120 – (1 × 4) = 116 4 × 29 = 116 1 Use the compensation strategy to answer the questions. The first one has been done for you. 20 3 3 × ________ – ________ = a 19 × 3 = ________ 57 8 30 8 b 8 × 29 = ________ × ________ – ________ = 232 20 6 12 c 18 × 6 = ________ × ________ – ________ = 108 7 40 7 d 7 × 39 = ________ × ________ – ________ = 273 10 30 5 e 28 × 5 = ________ × ________ – ________ = 140 We can also adjust up. Look how we do this with 6 × 62: 62 is close to 60. We can do 6 × 60 in our heads because we know 6 × 6 = 36 6 × 60 = 360 We have to then add 2 more lots of 6: 360 + 12 = 372 6 × 62 = 372 2 Use the compensation strategy and adjust up for these. The first one has been done for you. 40 3 3 a 41 × 3 = ________ × ________ + ________ = 123 80 4 4 b 81 × 4 = ________ × ________ + ________ = 324 20 9 18 c 22 × 9 = ________ × ________ + ________ = 198 30 9 18 d 32 × 9 = ________ × ________ + ________ = 288 7 60 14 e 7 × 62 = ________ × ________ + ________ = 434 Multiplication and Division Copyright © 3P Learning Would I use the compensation strategy with numbers such as 56 or 84? Why or why not? F 1 SERIES TOPIC 7 Mental multiplication strategies – compensation strategy 3 In this activity you’ll work alongside a partner. You’ll each need two dice and your own copy of this page. For each line, roll the dice to find the tens digit and then roll it again to find the multiplier. Your partner will do the same. Use the compensation strategy to mentally work out the answers to the problems. Tens Units Multiplier Answer 1 × = 9 × = 2 × = 1 × = 8 × = 1 × = 9 × = 8 × = 2 × = 1 × = a Check each other’s calculations. You may want to use a calculator. bNow, use the calculator to add your answers. The person with the highest score wins. 8 F 1 SERIES TOPIC Multiplication and Division Copyright © 3P Learning copy Check individual answers. Mental multiplication strategies – factors and multiples Factors are the numbers we multiply together to get to another number: factor factor × whole number = How many factors does the number 12 have? 4 × 3 = 12, 6 × 2 = 12, 1 × 12 = 12 4, 3, 6, 2, 1 and 12 are all factors of 12. 1 2 List the factors of these numbers: a 18 1 18 2 9 c 14 1 14 2 7 e 16 1 16 2 8 4 g 30 1 30 2 15 3 3 6 10 5 6 b 25 1 25 5 d 9 1 9 3 f 15 1 15 5 3 h 42 1 42 2 21 3 14 6 7 Fill the gaps in these sentences. The first one has been done for you. 1 or _____ 16 or _____ 2 or _____ 8 or _____ 4 people can share 16 lollies evenly. a _____ 1 or _____ 20 or _____ 2 or _____ 10 or _____ 4 or _____ 5 people can share 20 slices of pie evenly. b _____ 1 or _____ 24 or _____ 2 or _____ 12 or _____ 3 or _____ 8 or _____ 4 or _____ 6 people can share 24 cherries. c _____ 1 or _____ 30 or _____ 2 or _____ 15 or _____ 3 or _____ 10 or _____ 5 or _____ 6 people can share 30 pencils. d _____ 1 or _____ 5 people can share 5 balls evenly. e _____ 3 Use a calculator to help you find as many factors of 384 as you can: 1, 384 8, 48 2, 192 12, 32 3, 128 16, 24 A factor divides into a number evenly with no remainder. 4, 96 6, 64 Multiplication and Division Copyright © 3P Learning F 1 SERIES TOPIC 9 Mental multiplication strategies – factors and multiples Multiples are the answers we get when we multiply 2 factors. Think about the 3 times tables where 3 is always a factor. What are the multiples of 3? 3 × 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33 and 36 … 4 factor multiple = Fill in the gaps on these multiple boards: 4 a 5 b 9 c 7 d 8 10 18 14 12 15 27 21 16 20 36 28 20 25 45 35 24 30 54 42 28 35 63 49 Numbers can be either factors or multiples depending on where they sit in the number sentence. 5 10 Choose 2 numbers between 2 and 5 and put them in the first frame as factors. Your answer is the multiple. Now take that multiple and make it a factor in another number sentence. Write in the other factor and solve the problem. Then make the answer a factor again. Can you fill the grid? Use a calculator for the larger problems. The first one has been done for you. a 3 × 4 = 12 b 2 × 5 = 10 c 4 × 2 = 8 d 5 × 4 = 20 F 1 SERIES TOPIC 12 × 2 = 24 10 × 5 = 50 8 × 3 = 24 20 × 4 = 80 Multiplication and Division Copyright © 3P Learning 24 × 2 = 50 × 5 = 250 24 × 3 = 80 × 4 = 320 48 72 Sample answers – answers will vary. Mental division strategies – use multiplication facts Knowing our multiplication facts helps us with division as they do the reverse of each other. They are inverse operations. 3 × 5 = 15 15 ÷ 5 = 3 1 2 3 Use your knowledge of multiplication facts to help answer these division questions: a 56 ÷ 7 8 ________ × 7 = 56 56 ÷ 7 b 121 ÷ 11 11 × 11 = 121 ________ 121 ÷ 11 = c 72 ÷ 8 9 ________ × 8 = 72 72 ÷ 8 = 9 d 49 ÷ 7 7 ________ × 7 = 49 49 ÷ 7 = 7 e 36 ÷ 9 4 ________ × 9 = 36 36 ÷ 9 = 4 f 64 ÷ 8 8 ________ × 8 = 64 64 ÷ 8 = 8 g 108 ÷ 12 9 ________ × 12 = 108 108 ÷ 12 = 9 8 = 11 Now try these: a 81 ÷ 9 = 9 b 40 ÷ 5 = 8 c 21 ÷ 3 = 7 d 54 ÷ 6 = 9 e 42 ÷ 7 = 6 f 63 ÷ 9 = 7 g 36 ÷ 4 = 9 h 45 ÷ 9 = 5 i 39 ÷ 3 = 13 j 24 ÷ 6 = 4 Doing maths without knowing your multiplication facts is hard. Learning them makes your life much easier. It’s worth persevering to conquer them! Fill in the division wheels. Use multiplication facts to help you. a b 6 10 7 36 60 42 24 ÷6 6 48 30 18 5 c 4 3 9 1 8 6 8 1 81 54 72 9 ÷9 18 36 63 45 7 9 2 4 5 Multiplication and Division Copyright © 3P Learning 7 11 4 36 16 28 44 40 ÷4 32 8 10 24 8 6 2 F 2 SERIES TOPIC 11 Mental division strategies – use multiplication facts Knowing our families of facts is also helpful. 3 × 5 = 15 5 × 3 = 15 4 a 7 × 8 = 56 b 8 × 9 = 72 c 7 × 9 = 63 8 × 7 = 9 × 8 = 9 × 7 = 7 56 56 = 8 ÷ 8 = 7 72 ÷ 72 8 72 =9 63 ÷ ÷ 9 = 8 63 7 63 = 9 ÷ 9 = 7 Write down another multiplication fact and two division facts for each question. a 6 × 7 = 42 7x6 = 42 b 5 × 9 = 45 c 9 × 6 = 54 6 x 9 = 54 9 x 5 = 45 42 ÷ 6 = 7 45 ÷ 9 = 5 54 ÷ 6 = 9 42 ÷ 7 = 6 45 ÷ 5 = 9 54 ÷ 9 = 6 d 17 × 8 = 136 8 x 17 = 136 136 ÷ 8 = 17 136 ÷ 17 = 8 6 15 ÷ 3 = 5 Complete the following patterns. How many more multiplication and division facts can you find, given the first fact? 56 ÷ 5 15 ÷ 5 = 3 Look at these two division facts: f 11 × 21 = 231 e 12 × 8 = 96 21 x 11 = 231 8 x 12 = 96 231 ÷ 21 = 11 96 ÷ 8 = 12 231 ÷ 11 = 21 96 ÷ 12 = 8 20 ÷ 5 = 4 and 20 ÷ 4 = 5 Imagine you’re explaining to a younger child how they’re related yet different. How would you do it? What would you say/write/draw? 20 ÷ 5 = 4 20 ÷ 4 = 5 Sample answer. 12 F 2 SERIES TOPIC Multiplication and Division Copyright © 3P Learning Mental division strategies – divide by 10s, 100s and 1 000s When we divide by 10 we move the number one place value to the right. When we divide by 100 we move the number two place values to the right. When we divide by 1 000 we move the number three place values to the right. Look what happens to 45 000 when we apply these rules: 1 Thousands Hundreds Tens Units 4 5 4 0 5 4 0 0 5 4 0 0 0 5 ÷ 10 ÷ 100 ÷ 1 000 Divide the following numbers by 10, 100 and 1 000: a c 2 Ten Thousands T Th Th H T U 4 5 0 0 0 4 5 0 0 ÷ 10 4 5 0 ÷ 100 4 5 ÷ 1 000 b d T Th Th H T U 8 5 0 0 0 8 5 0 0 ÷ 10 8 5 0 ÷ 100 8 5 ÷ 1 000 T Th Th H T U 4 3 0 0 0 4 3 0 0 ÷ 10 4 3 0 ÷ 100 4 3 ÷ 1 000 T Th Th H T U 8 8 0 0 0 8 8 0 0 ÷ 10 8 8 0 ÷ 100 8 8 ÷ 1 000 Draw lines to match the answers with the questions: a What number is one thousand times smaller than 32 000? b What number is one hundred times smaller than 32 000? c What number is one hundred times smaller than 95 000? d What number is ten times smaller than 95 000? e What number is one hundred times smaller than 8 800? f What number is ten times smaller than 8 800? Multiplication and Division Copyright © 3P Learning 9 500 88 950 880 320 32 F 2 SERIES TOPIC 13 Mental division strategies – halving strategy When the two numbers seem too large to work with in our heads, we can halve them till we get to a division fact we recognise. Both numbers must be even for this to work. 126 ÷ 14 (half 126) ÷ (half 14) 63 ÷ 7 = 9 1 Practise your halving. The first one has been done for you. a 56 36 84 96 2 3 14 32 16 28 halve 18 42 48 b 24 48 72 144 192 12 24 halve 36 72 96 c 50 500 1 000 250 100 25 250 halve 500 125 50 Halve each number to get to a recognisable division fact. The first one has been done for you. a 112 ÷ 14 56 7 ________ ÷ ________ = 8 b 144 ÷ 16 8 72 ________ ÷ ________ = 9 c 96 ÷ 12 48 6 ________ ÷ ________ = 8 d 220 ÷ 4 110 2 ________ ÷ ________ = 55 e 162 ÷ 18 81 9 ________ ÷ ________ = 9 Match the problems with their halved equivalents. Then solve the problem. The first one has been done for you. a 90 ÷ 18 60 ÷ 6 = 5 b 64 ÷ 16 24 ÷ 8 = 4 c 120 ÷ 12 35 ÷ 7 = 10 d 70 ÷ 14 45 ÷ 9 = 5 e 144 ÷ 24 72 ÷ 12 = 6 f 48 ÷ 16 32 ÷ 8 = 3 F 2 SERIES TOPIC Multiplication and Division Copyright © 3P Learning Mental division strategies – halving strategy Sometimes we need to keep halving until we reach an easy division fact. 144 ÷ 36 72 ÷ 18 36 ÷ 9 = 4 4 5 Keep halving until you get to a fact you can work with. If you can do it in your head, just fill in the last box. Otherwise, use the lines to help you. 108 18 54 9 a 216 ÷ 36 = ________ ÷ ________ = ________ ÷ ________ = 6 14 49 7 98 b 196 ÷ 28 = ________ ÷ ________ = ________ ÷ ________ = 7 112 16 56 8 c224 ÷ 32 = ________ ÷ ________ = ________ ÷ ________ = 7 84 12 42 6 d 168 ÷ 24 = ________ ÷ ________ = ________ ÷ ________ = 7 72 18 36 9 e144 ÷ 36 = ________ ÷ ________ = ________ ÷ ________ = 4 144 36 72 18 f 288 ÷ 72 = ________ ÷ ________ = ________ ÷ ________ = 4 Draw lines to connect numbers that could be doubled or halved to reach each other. 16 10 48 25 32 20 40 64 96 60 30 128 256 125 192 250 80 100 6 120 50 Work with a partner to solve this problem using halving: You have an after school job at the local lolly shop, making up the mixed lolly bags. Today, you have to evenly share 288 freckles among 48 bags. How many freckles will you put in each bag? Show each halved sum. 288 ÷ 48 144 ÷ 24 72 ÷ 12 36 ÷ 6 = 6 Multiplication and Division Copyright © 3P Learning F 2 SERIES TOPIC 15 Mental division strategies – split strategy Division problems also become easier if you split the number to be divided into recognisable facts. Look at the problem 144 ÷ 9 Can we divide 144 into 2 multiples of 9? We can divide it into 54 and 90. These are both easily divided by 9. Then we add the two answers together. 1 90 54 ÷ 9 ÷9 10 + 6 = 16 Use the split strategy to divide these numbers. Use the clues to guide you: a 112 ÷ 8 b 85 ÷ 5 c 50 35 _____ _____ 18 60 _____ _____ ÷ 8 ÷8 10 + _____ 4 _____ = d 14 64 ÷ 4 ÷ 5 ÷5 7 10 + _____ _____ = e 17 91 ÷ 7 ÷ 6 ÷6 10 + _____ 3 _____ = f 21 70 _____ _____ 80 64 _____ _____ ÷ 4 ÷4 6 10 = _____ + _____ 16 ÷ 7 ÷7 3 + _____ 10 = _____ 13 ÷ 8 60 ÷ ______ 6 ______ = 15 = 15 = 18 8 48 ÷ ______ ______ d 144 ÷ 8= 96 ÷ ______ 8 ______ 18 b 105 ÷ 7 30 ÷ ______ 6 ______ 7 70 ÷ ______ ______ Hmmm … 91 ÷ 7. The unit digit helps me here. What multiple of 7 ends in 1? I know, 21. So that makes the other number 70! 7 35 ÷ ______ ______ c 72 ÷ 4 48 ÷ ______ 4 ______ 24 ÷ ______ 4 ______ F 2 SERIES TOPIC Multiplication and Division Copyright © 3P Learning ÷8 10 + _____ 8 _____ = Now try these: a 90 ÷ 6 13 144 ÷ 8 24 40 _____ _____ 16 78 ÷ 6 80 32 _____ _____ 2 144 ÷ 9 18 Mental division strategies – split strategy 3 Play this game with a partner. Use one copy of this page between you. Cut out the problems on the left and stack them face up. Cut out and spread the other cards face up. Work together (or race) to find two numbers you could divide to solve the problem on the top card of the pile. One card in the pair will be grey, the other white. For example, if the problem was 76 ÷ 4, you could locate 36 and 40. 96 ÷ 4 45 90 75 ÷ 5 25 21 87 ÷ 3 60 50 98 ÷ 7 80 70 135 ÷ 9 55 36 78 ÷ 6 30 60 112 ÷ 8 60 60 51 ÷ 3 27 32 95 ÷ 5 24 40 84 ÷ 6 28 18 Multiplication and Division Copyright © 3P Learning copy F 2 SERIES TOPIC 17 Mental division strategies – tests of divisibility Divisibility tests tell us if a number can be divided evenly by another (that is with no remainders). 1 Use the rules to test out the numbers in the last column. The first two have been done for you: Divisible by Rule Test Is 458 divisible by 2? 2 A number is divisible by 2 if it’s even (ends in 0, 2, 4, 6 or 8). Yes, because it ends in an even number. Is 7 281 divisible by 3? 3 A number is divisible by 3 if the sum of its digits is divisible by 3. 7 + 2 + 8 + 1 = 18 Yes, because 18 is divisible by 3. Is 3 912 divisible by 4? 4 A number is divisible by 4 if the number made by the last 2 digits is divisible by 4. Yes, because 12 is divisible by 4. Is 455 divisible by 5? 5 A number is divisible by 5 if there’s a 0 or 5 in the units place. Yes, because 5 is in the units place. Is 74 160 divisible by 8? 8 A number is divisible by 8 if the last 3 digits are divisible by 8. Yes, because 160 ÷ 8 = 20 Is 6 345 divisible by 9? 9 A number is divisible by 9 if the sum of its digits is divisible by 9. 6 + 3 + 4 + 5 = 18 Yes, because the digits add to 18 and that is divisible by 9. 18 ÷ 9 = 2 Is 5 680 divisible by 10? 10 18 F 2 SERIES TOPIC A number is divisible by 10 if there is a zero in the units place. Yes, because there is a zero in the units place. Multiplication and Division Copyright © 3P Learning Mental division strategies – tests of divisibility 2 These numbers can all be divided with no remainders. Work with a partner to find the rule/s that can be used to divide them. Fill in the tables. 36 90 84 99 50 72 456 330 888 120 981 548 1 025 3 486 6 993 1 256 9 050 10 072 ÷4 36 456 888 120 ÷5 ÷9 36 90 99 50 36 120 90 330 72 1 025 548 981 9 050 1 256 72 90 10 072 6 993 330 981 3 486 6 993 ÷8 72 84 ÷3 Numbers may go onto more than 1 table! 456 456 888 120 120 99 1 256 84 10 072 888 72 Multiplication and Division Copyright © 3P Learning F 2 SERIES TOPIC 19 Written methods – contracted multiplication H 1 1 1 T U 5 6 × 3 4 1 6 8 Solve these problems using contracted multiplication. Estimate first: e: a H 2 T U 2 7 × e: 8 H 3 1 U 1 5 4 5 2 U 4 7 9 8 H 1 2 1 8 6 7 5 4 7 0 1 000 f H 4 1 2 T U 9 4 × 2 5 9 7 0 Solve these word problems. Show how you worked them out: aDan’s dad has resorted to bribery to counteract Dan’s PlayStation addiction. For every evening, Dan spends away from the PlayStation, his dad pays him $3. So far, Dan has racked up an impressive 27 nights (though he looks like breaking any day now). How much money does this equate to? bDan’s mum thinks she might get in on the action too and pays Dan $4 for every week that he puts his dishes in the dishwasher and his dirty clothes in the basket. Dan is less keen on this plan but does manage 33 weeks in 1 year. How much has he made out of this scheme? 20 U 5 e: U 2 7 2 5 1 T × 8 T × H 2 560 e 750 c 4 e: 3 9 2 T × 1 T × H 1 900 e: 1 000 b 3 9 d e: 990 3 2 Contracted multiplication is one way to solve a multiplication problem. First we use our mental strategies to estimate an easier problem: 3 × 150 = 450. The answer will be around 450. We start with the units. 3 × 6 is 18 units. We rename this as 1 ten and 8 units. We put 8 in the units column and carry the 1 to the tens column. 3 × 5 plus the carried 1 is 16 tens. We rename this as 1 hundred and 6 tens. We put 6 in the tens column and carry the 1 to the hundreds column. 3 × 1 plus the carried 1 is 4 hundreds. We put 4 in the hundreds column. F 3 SERIES TOPIC Multiplication and Division Copyright © 3P Learning 2 2 × 7 3 8 $81 1 1 3 × 3 4 1 3 2 $132 Written methods – contracted multiplication 3 Below are Jess and Harry’s tests. Check them and give them a mark out of 5. If they made mistakes, give them some feedback as to where they went wrong. Jess 1 3 1 Harry 8 1 7 × 2 7 7 4 1 1 9 × 7 3 2 0 3 × 4 1 0 9 3 6 × 7 1 2 0 8 4 0 1 × 8 0 7 6 1 9 8 3 3 2 0 3 × 1 4 1 6 9 3 6 × 3 7 3 1 3 0 8 4 0 1 × 3 3 3 3 7 2 1 4 7 7 7 7 7 × 3 1 8 2 3 3 6 1 × 7 7 3 3 7 2 8 7 7 Forgot to carry. Did not multiply the zero. Multiplication and Division Copyright © 3P Learning F 3 SERIES TOPIC 21 Written methods – extended multiplication H 2 T 3 6 7 1 9 0 0 × 1 U 4 3 2 0 0 2 Extended multiplication is another way of solving problems. In extended multiplication we multiply the units, tens and hundreds separately then add the answers together. (3 × 4) (3 × 30) (3 × 200) Use a calculator to help you work out the values you could expect when multiplying the following. Tick the columns: T TH 2 a a unit by a unit 9 × 7 b a ten by a unit 43 × 5 c a hundred by a unit d a ten by a ten e a ten by a hundred 126 × 7 13 × 72 3 55 × 120 H T U 3 3 3 3 3 3 3 3 3 3 3 3 3 3 Complete using extended multiplication. Estimate first: e: a e: 490 2 4 × 5 2 0 (2 × 5) 8 0 (2 × 40) 4 0 0 (2 × 200) 4 9 0 d 3 SERIES TOPIC 5 2 2 7 3 7 4 (7 × 2) 3 5 0 (7 × 50) 2 8 0 0 (7 × 400) 3 1 6 4 e: 9 5 6 (8 × 7) 1 6 0 (8 × 20) 2 4 0 0 (8 × 300) 2 6 1 6 1 4 1 × 2 9 1 9 8 (2 × _____) 1 2 8 (9 × _____) 1 4 70 0 (2 × _____) 9 10 0 (9 × _____) 4 0 200 0 (2 × _____) 3 6 0 400 0 (9 × _____) 5 5 8 3 7 0 8 Multiplication and Division Copyright © 3P Learning 7 8 3 600 e 2 2 × 1 1 2 600 c 560 × F 4 × 1 e: 3 100 b e: 22 TH 2 × 2 would give me a unit only. But 8 × 6 would give me tens and units. I’ll tick both columns. Written methods – extended multiplication 3 Use extended multiplication to solve these problems: aJack and his 2 friends bought tickets to the World Cup. Each ticket costs $124. How much did they spend altogether? e: bJack has a paper round and earns $7 per day. He works for 18 days and saves it all. Has he earned enough to pay for his World Cup ticket? e: 360 $ 1 2 × $ 4 $ 3 × 1 8 7 1 2 (3 × 4) 5 6 (7 × 8) 6 0 (3 × 20) 7 0 (7 × 10) 3 0 0 (3 × 100) 2 6 3 7 2 $ cYusuf’s highest Level 1 Live Mathletics score is 112. Yep, he’s fast. If he scores this 7 times in a row, how many correct answers has he achieved? e: 1 × 1 dKyra’s class of 24 all had to stay in for 11 minutes of their recess. Something to do with too much talking. How many minutes is this in total? e: 770 1 4 120 240 2 × 7 1 4 (7 × 2) 7 0 (7 × 10) 7 0 0 (7 × 100) 7 8 4 2 4 1 1 4 (1 × 4) 2 0 (1 × 20) 4 0 (10 × 4) 2 0 0 (10 × 20) 2 6 4 Once you have the hang of extended multiplication, you can apply it to larger numbers. Try these: a 2 2 9 3 8 4 3 5 2 0 (2 × 5) 2 7 (3 × 9) 1 6 (2 × 8) 8 0 (2 × 40) 6 0 (3 × 20) 6 0 (2 × 30) 4 0 0 (2 × 200) 9 0 0 (3 × 300) 4 0 0 (2 × 200) 1 5 0 (30 × 5) 3 6 0 (40 × 9) 4 0 0 (50 × 8) 1 2 0 0 (30 × 40) 8 0 0 (40 × 20) 1 5 0 0 (50 × 30) 6 0 0 0 (30 × 200) 1 2 0 0 0 (40 × 300) 1 0 0 0 0 (50 × 200) 7 8 4 0 1 4 1 4 7 1 2 3 7 6 × 4 5 3 2 1 b 3 × Multiplication and Division Copyright © 3P Learning c 2 × F 3 SERIES TOPIC 23 Written methods – short division In short division, we use our knowledge of multiplication to help us. We can split 936 into 900 + 30 + 6. 900 divided by 3 is 300, so we put a 3 in the hundreds place. 3 1 2 30 divided by 3 is 10, so we put a 1 in the tens place. 3 9 3 6 6 divided by 3 is 2, so we put a 2 in the units place. 936 ÷ 3 = 312 1 Divide these numbers: a 4 d 9 g 3 b 2 1 8 4 1 1 0 9 9 0 3 3 3 9 9 9 5 e 4 h 2 c 1 1 5 5 1 2 1 4 8 4 2 3 1 4 6 2 3 f 6 i 3 9 3 1 1 1 6 6 6 2 3 1 6 9 3 Decide how you’ll split these numbers and then divide. Remember to put in zeros as needed. a 5 c 9 24 1 In these problems, if there are no tens in a number we put a 0 in to show this and also to hold the place of the other numbers! Sometimes it’s easier to split the numbers differently. We can also split 936 into 900 + 36. 900 divided by 3 is 300 so we put a 3 in the hundreds place 3 1 2 36 divided by 3 is 12. We put the 1 in the tens 3 9 3 6 place and the 2 in the units place. 936 ÷ 3 = 312 2 3 1 0 3 5 1 5 1 0 3 9 2 7 F 3 SERIES TOPIC b 3 d 4 2 2 3 6 6 9 2 0 1 8 0 4 Multiplication and Division Copyright © 3P Learning e 4 2 0 3 8 1 2 Written methods – short division with remainders Sometimes numbers don’t divide evenly. The amount left over is called the remainder. Look at 527 divided by 5. 500 divided by 5 is 100. 1 0 5 r2 27 divided by 5 is 5 with 2 left over (this is the remainder). 5 5 2 7 This can be written as r 2. 527 ÷ 5 = 105 r 2. 1 Divide these 2 digit numbers. Each problem will have a remainder. a 8 9 d 7 5 1 2 6 3 5 2 b 1 1 4 7 1 2 4 9 4 e r3 4 r3 c 0 6 3 8 1 0 6 2 6 f r1 6 r2 r2 Divide these 3 digit numbers. Each problem will have a remainder. a 5 d 9 3 r3 1 1 1 5 5 7 1 1 0 9 9 4 r2 b 3 r4 e 4 2 2 0 6 6 1 2 1 1 8 4 5 r1 c 4 r1 f 6 1 2 0 4 8 1 1 0 6 6 3 8 r1 r2 Solve these problems: aGiovanni’s Nonna has given him a bag of gold coins to share among him and his two sisters. There are 47 gold coins altogether. How many does each child get if they’re shared evenly? How would you suggest they deal with the remainder? 15 Answers will vary. ___________________________________________________________________________ bYou have 59 jubes to add to party bags. Each bag gets 5 jubes. How many full party bags can you make? 5 1 1 5 9 r4 Multiplication and Division Copyright © 3P Learning 11 r 4 F 3 SERIES TOPIC 25 Written methods – short division with remainders There are 3 ways of expressing remainders. How we do it depends on how we’d deal with the problem in the real world. Look at: 4 0 5 5 2 7 r2 One way is to write r 2 as in the example above. We use this when we don’t care about being absolutely precise and when the remainder can’t be easily broken up. An example would be sharing 527 jelly beans among 5 people. Solve these problems expressing the remainders as r. a Share 126 blue pencils among 4 people. 4 5 5 1 1 3 1 2 6 b Share 215 paper clips among 7 people. r2 7 2 We can also express a remainder as a fraction. We do this when we can easily share the remainder. For example, 19 cakes shared among 3 people is 6 and one third each. Solve these problems expressing the remainder as a fraction: a Share 13 pizzas among 4 people. 3 0 1 5 r5 6 3 1 1 3 9 b Share 50 sandwiches among 3 people. 3 4 6 1 1 4 3 3 1 6 5 0 2 3 We express remainders as decimals when we must be absolutely precise. Sharing dollar amounts is a good example of this. We add the cents after the decimal point to help us. Try these: a Share 12 dollars among 4 people. b Share 27 dollars between 2 people. 4 26 1 F 3 SERIES TOPIC 3 0 0 2 0 0 2 1 3 5 0 2 7 0 0 Multiplication and Division Copyright © 3P Learning 27 divided by 2 is 13. Now we have one dollar left. How how many cents is half of one dollar? Written methods – solving problems We regularly come across multiplication and division problems in our everyday life. It doesn’t matter which strategy we use to solve them, we can choose the one that suits us or the problem best. 1 One real-life problem is comparing prices to find the best deal. It’s easy if the prices and amounts are the same but what if the amounts are different? Use a strategy to help you find the best deal on these: a b 2 100 g 300 g $1.95 $5.43 1 1 9 × 5 3 5 8 or 5 1 3 2 5 8 1 4 3 1 1 3 9 5 × 2 7 9 or 0 2 4 2 5 8 5 0 $5.43 for 300 g Best deal is __________________________ $3.95 for 500 g Best deal is __________________________ c d 10 pack CD Single CD 500 ml $2.75 $22.90 2 litres $2.80 $1.40 $22.90 ÷ 10 = $2.29 or $2.75 × 10 = $27.50 1 1 1 4 × 0 4 5 10 pack CD Best deal is __________________________ 2 $8.50 $3.95 6 0 or 4 0 7 0 2 8 0 2 litres Best deal is __________________________ You go to the service station with your weekly pocket money of $5. When you take a $1.75 chocolate bar to the counter, they offer you the special of 3 bars for $4.50. Which is a better deal? Show why. 2 1 3 4 5 1 0 or 5 0 1 1 7 × 5 3 5 2 Best deal is 3 bars for $4.50- $1.50 each. Cheaper than $1.75 each. 5 Multiplication and Division Copyright © 3P Learning F 3 SERIES TOPIC 27 Written methods – solving problems 3 You’re planning a trip to the Wet and Wild theme park and there are many ticket options. Use a strategy of your choice and the price list below to answer the following questions: Entry Extras 1-day pass $32 5-minute helicopter ride $42 2-day pass $48 10-minute helicopter ride $74 Annual pass $99 30-minute helicopter ride $209 Individual rides $12 Sunset cruise $12 10-ride pass $95 Lunch cruise $22 Order online $5 discount Swim with the dolphins $75 a If you buy a 2-day pass, what is the cost per day? $24 b How much cheaper is this option than buying two 1-day passes? $16 cIf you bought an annual pass, how many times would you need to visit to make it a better option than buying either a 1-day or 2-day pass? dWhat if you choose just the rides? How much would you save if you bought the 10-ride pass instead of the individual rides? $25 e If you took a 5-minute helicopter ride, what would be the cost per minute? $8.40 f What about if you chose the 10-minute flight option? What would be the cost per minute? $7.40 g Plan a day’s itinerary for you and a partner. How much will this cost? 28 5 F 3 SERIES TOPIC Multiplication and Division Copyright © 3P Learning Answers will vary. Crack the code What to do apply Use the code below to work out the hidden message. M A T H L E T I C S __ __ __ __ __ __ __ __ __ __ 2 1 3 6 4 5 3 8 7 I S __ __ 9 8 1 A is ______ F = H + L 10 F = ______ 2 M × M = M + M M is______ E = F ÷ 2 5 E = ______ 8 I = ______ A × A = A T – M = A 3 T is ______ 2 × L = I T + T = H 6 H is ______ 7 (2 × L) – A = C C = ______ H – M = L 4 L is ______ F + A = N 11 N = ______ 3 × L = U 12 U is ______ 3 × T = S 9 S = ______ What to do 9 10 12 11 Once I work out the first couple, the rest come easily! Try this one: A S T R O N A U T S __ __ __ __ __ __ __ __ __ __ 2 9 4 12 13 8 T A L L E R __ __ __ __ __ __ 4 F U N __ __ __ 2 6 6 3 2 7 4 9 I N __ __ 12 0 8 2 A × A = A + A A is______ If two letters are together, we read them as a tens digit and a units digit. A R E __ __ __ 2 12 3 S P A C E __ __ __ __ __ 9 1 2 5 3 L + E = S 9 S is______ A + A = T 4 T is ______ N – N = I 0 I is______ T × 2 = N 8 N is______ U – A = C 5 C is______ AT ÷ N = E 3 E is______ 1 S – (2 × T) = P P is______ 2 × E = L 6 L is ______ 13 2 × U – P = O O is______ E + T = U 7 U is______ S + E = R Multiplication and Division Copyright © 3P Learning 12 R is______ F 4 SERIES TOPIC 29 Smart buttons Getting ready What to do apply In this activity, you’ll use your knowledge of multiplication, division, subtraction and addition to find as many number statements you can to create one number. Using ONLY the number 2, +, ×, – and ÷ keys on your calculator, find as many ways as you can to create the number 13. For example, you could make: 22 + 2 + 2 = 26 ÷ 2 = 13 Record your statements on a piece of paper. Now, compare your answers with a partner’s. How many did they find? Can you supplement each other’s lists? What’s the longest statement? What’s the shortest? What to do Choose another number to make and see how many statements you can find or challenge a partner to a competition. Set a time limit and see who can find the most ways to make 15 within the time span. Answers will vary. Bugsinvestigate Getting ready What to do Use your knowledge of multiples to help you work out how many boy bugs and girl bugs there are in the problem below. Listing all the multiples is a strategy that would help. Girl bugs have 4 splodges on their backs, boy bugs have 9. Altogether there are 48 splodges. Work out how many girl bugs and how many boy bugs there are. 3 girl bugs. 4 boy bugs. What to do next What if girl bugs have 8 splodges and boy bugs have 6 and there are 120 splodges altogether? How many different answers can you find? Answers will vary. 30 F 4 SERIES TOPIC Multiplication and Division Copyright © 3P Learning Puzzlesapply What to do a 2 × Use your knowledge of multiplication to work out the missing values: 8 b 3 8 d e 1 × 9 g 2 9 2 6 8 6 8 1 4 0 2 f 3 5 8 2 3 × 8 6 5 8 4 5 6 2 7 3 9 2 4 2 4 3 1 2 6 1 6 8 0 1 1 2 0 1 8 0 6 1 5 1 2 × 4 What to do 5 4 h 7 4 × 3 2 4 0 8 × × 1 4 2 4 c 2 × 8 7 7 i × Fill in the multiplication and division tables by working out the missing digits. The arrows show you some good starting places. 8 9 × 5 2 3 8 4 20 8 12 32 7 35 14 21 56 9 45 18 27 72 24 36 96 × 10 8 7 6 × 2 2 20 16 14 12 12 24 96 108 48 5 50 40 35 30 3 6 24 27 12 × 3 4 9 8 6 60 48 42 36 7 14 56 63 28 2 6 8 18 16 3 30 24 21 18 6 12 48 54 24 11 33 44 99 88 7 21 28 63 56 8 24 32 72 64 Multiplication and Division Copyright © 3P Learning 4 12 60 F 4 SERIES TOPIC 31 Puzzlesapply What to do Complete this crossnumber puzzle: 1 2 2 1 3 2 4 1 6 What to do 5 4 2 9 5 0 7 8 2 1 1 1 10 4 5 2 1 4 9 1 3 0 0 Down 1 60 ÷ 5 1 11 × 11 2 25 × 5 2 12 × 10 3 7 × 6 3 7 × 7 4 15 × 6 5 66 ÷ 6 7 7 × 3 6 12 × 12 9 9 × 6 8 39 ÷ 3 10 6 × 50 Test your speed and accuracy. Race against a partner or the clock to complete each table: ÷8 ÷3 ÷7 56 7 9 3 21 3 16 2 6 2 7 1 64 8 18 6 14 2 80 10 12 4 70 10 32 4 24 8 49 7 72 9 30 10 28 4 24 3 27 9 42 6 8 1 33 11 35 5 Time: What to do Across Time: Use the “guess, check and improve” strategy to solve this problem. You could use a calculator to help if you wish. Time: If the decimals are confusing me, I can change the amounts to 310 cents and 295 cents. Tracey paid $3.10 for 7 lolly snakes and 4 sherbets. Madison paid $2.95 for 4 lolly snakes and 7 sherbets. How much does one lolly snake cost? How much does one sherbet cost? 1 lolly snake = 30¢ 1 sherbet = 25¢ 32 F 4 SERIES TOPIC Multiplication and Division Copyright © 3P Learning Multiplication facts 1 Name_____________________ Using a lead pencil complete the grid facts. Once the grid has been checked, colour all your correct facts. How many do you know? How many do you still need to learn? × 4 2 3 7 6 12 5 10 11 1 9 8 2 3 7 6 12 5 10 11 1 9 8 2 4 8 2 Try these sets: × 4 7 5 10 Skills Not yet Kind of Got it • 2× • 4× • 8× • 7× • 5× • 10 × Series F Topic 1 Assessment Copyright © 3P Learning 33 Multiplication facts 3 Name_____________________ Using a lead pencil complete the grid facts. Once the grid has been checked, colour all your correct facts. How many do you know? How many do you still need to learn? × 4 2 3 7 6 12 5 10 11 1 9 8 2 3 7 6 12 5 10 11 1 9 8 3 6 9 4 Try these sets: × 4 11 12 0 1 Skills Not yet Kind of Got it • 3× • 6× • 9× • 11 × • 12 × • 0× • 1× 34 Series F Topic 1 Assessment Copyright © 3P Learning Multiplication facts 1 2 Name_____________________ Using a lead pencil complete the grid facts. Once the grid has been checked, colour all your correct facts. How many do you know? How many do you still need to learn? × 4 2 3 7 6 12 5 10 11 1 9 8 2 8 4 6 14 12 24 10 20 22 2 18 16 4 16 8 12 28 24 48 20 40 44 4 36 32 8 32 16 24 56 48 96 40 80 88 8 72 64 Try these sets: × 4 2 3 7 6 12 5 10 11 1 9 8 7 28 14 21 49 42 84 35 70 77 7 63 56 5 20 10 15 35 30 60 25 50 55 5 45 40 10 40 20 30 70 60 120 50 100 110 10 90 80 Skills Not yet Kind of Got it • 2× • 4× • 8× • 7× • 5× • 10 × Series F Topic 1 Assessment Copyright © 3P Learning 35 Multiplication facts 3 4 Name_____________________ Using a lead pencil complete the grid facts. Once the grid has been checked, colour all your correct facts. How many do you know? How many do you still need to learn? × 4 2 3 7 6 12 5 10 11 1 9 8 3 12 6 9 21 18 36 15 30 33 3 27 24 6 24 12 18 42 36 72 30 60 66 6 54 48 9 36 18 27 63 54 108 45 90 99 9 81 72 Try these sets: × 4 2 3 7 6 12 5 10 11 1 9 8 11 44 22 33 77 66 132 55 110 121 11 99 88 12 48 24 36 84 72 144 60 120 132 12 108 96 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 2 3 7 6 12 5 10 11 1 9 8 Skills Not yet Kind of Got it • 3× • 6× • 9× • 11 × • 12 × • 0× • 1× 36 Series F Topic 1 Assessment Copyright © 3P Learning Mental multiplication strategies 1 Show how you would solve 18 × 4 using: a b the doubling strategy 2 c the split strategy the compensation strategy Use a strategy of your choice to solve the following problems. Show how you arrived at your answer. a 28 × 4 3 Name_____________________ bIn 2000, a new world record was set when 18 people crammed into a mini. How many people would fit into 9 minis? You can choose from the payment methods below for your new after school job as chief taster at an ice cream shop. You work Monday to Friday, 4 pm to 6 pm. Which method would earn you the most money in 4 weeks and why? a Daily payments of $9. b Weekly payments of $42. c Fortnightly payments of $75. Series F Topic 1 Assessment Copyright © 3P Learning 37 Mental multiplication strategies 4 Multiply these numbers: a 10 × 43 5 6 7 Name_____________________ b 10 × $92 = = c 100 × 43 = d 100 × $92 = e 1 000 × 43= f 1 000 × $92= Use patterns to help solve these: a 5 × 2 _____________ 5 × 20 _____________ 5 × 200 _____________ b 2 × 9 _____________ 2 × 90 _____________ 2 × 900 _____________ c 6 × $4 _____________ 6 × $40 _____________ 6 × $400 _____________ What number is: a 100 times larger than 42? b 1 000 times larger than 135? c 30 times larger than 8? d 200 times larger than 7? List all the factors of the following numbers: List the first 5 multiples of: 36 5 24 7 45 4 18 3 Skills Not yet Kind of Got it • Recognises and uses a range of mental multiplication strategies doubling split compensation • Solves mental multiplication problems using strategy of choice • Applies strategies to real life word problems • Multiplies by numbers ending in zeros • Names factors and multiples of numbers to 50 38 Series F Topic 1 Assessment Copyright © 3P Learning Mental multiplication strategies 1 Show how you would solve 18 × 4 using: a b 18 × 4 18 × 2 = 36 36 × 2 = 72 c 18 × 4 (10 × 4) + (8 × 4) 40 + 32 = 72 the doubling strategy 2 the split strategy 18 × 4 = 20 × 4– 8 = 72 the compensation strategy Use a strategy of your choice to solve the following problems. Show how you arrived at your answer. a 28 × 4 3 Name_____________________ bIn 2000, a new world record was set when 18 people crammed into a mini. How many people would fit into 9 minis? 28 × 4 = 112 18 × 9 = 162 Working out will vary. Working out will vary. You can choose from the payment methods below for your new after school job as chief taster at an ice cream shop. You work Monday to Friday, 4 pm to 6 pm. Which method would earn you the most money in 4 weeks and why? a Daily payments of $9. 9 × 5 = 45, 45 × 4 = $180 b Weekly payments of $42. 42 × 4 = $168 c Fortnightly payments of $75. 75 × 2 = $150 You would earn the most with daily payments of $9 because you multiply it by days and weeks. Series F Topic 1 Assessment Copyright © 3P Learning 39 Mental multiplication strategies 4 Multiply these numbers: a 10 × 43 5 6 = b 10 × $92 430 = $920 c 100 × 43 = 4 300 d 100 × $92 = $9 200 e 1 000 × 43= 43 000 f 1 000 × $92= $92 000 Use patterns to help solve these: 10 a 5 × 2 _____________ 100 5 × 20 _____________ 5 × 200 1 000 _____________ 18 b 2 × 9 _____________ 180 2 × 90 _____________ 2 × 900 1 800 _____________ $24 c 6 × $4 _____________ $240 6 × $40 _____________ $2 400 6 × $400 _____________ What number is: a 100 times larger than 42? 4 200 c 30 times larger than 8? 7 Name_____________________ 240 List all the factors of the following numbers: b 1 000 times larger than 135? d 200 times larger than 7? 135 000 1 400 List the first 5 multiples of: 36 1, 36, 2, 18, 6, 4, 9, 3, 12 5 5 10 15 20 25 24 1, 24, 2, 12, 4, 6, 3, 8 7 7 14 21 28 35 45 1, 45, 5, 9, 3, 15 4 4 8 12 16 20 18 1, 18, 2, 9, 3, 6 3 3 6 9 12 15 Skills Not yet Kind of Got it • Recognises and uses a range of mental multiplication strategies doubling split compensation • Solves mental multiplication problems using strategy of choice • Applies strategies to real life word problems • Multiplies by numbers ending in zeros • Names factors and multiples of numbers to 50 40 Series F Topic 1 Assessment Copyright © 3P Learning Mental division strategies 1 Name______________________ Solve these division problems: a 40 ÷ 5 = b 36 ÷ 6 = c 21 ÷ 3 = d 54 ÷ 6 = e 49 ÷ 7 = f 48 ÷ 8 = g 500 ÷ 10 = h 6 000 ÷ 100= i 55 000 ÷ 1 000= 2 Show how you would use the halving strategy to solve 96 ÷ 24: 3 Use a strategy of your choice to solve these division problems. Show how you arrived at your answer. aThe 4 Herringer kids want to buy a Karaoke machine costing $192 for their mother’s birthday. Show how they could mentally work out each kid’s share of the cost. Finish this split strategy problem to solve 98 ÷ 7: b85 swimmers are divided into 5 equal teams. How many swimmers in each team? Skills Not yet Kind of Got it • Uses knowledge of multiplication facts to solve division problems • Solves division problems using strategy of choice • Divides by tens, hundreds, thousands • Recognises and uses a range of mental division strategies halving split other • Applies strategies to real life problems Series F Topic 2 Assessment Copyright © 3P Learning 41 Mental division strategies 1 Solve these division problems: a 40 ÷ 5 = 8 b 36 ÷ 6 = 6 c 21 ÷ 3 = 7 d 54 ÷ 6 = 9 e 49 ÷ 7 = 7 f 48 ÷ 8 = 6 g 500 ÷ 10 = 2 Name______________________ h 6 000 ÷ 100= 50 Show how you would use the halving strategy to solve 96 ÷ 24: i 55 000 ÷ 1 000= 60 55 Finish this split strategy problem to solve 98 ÷ 7: 35 ÷ 7= 5 98 ÷ 7 96 ÷ 24= 48 ÷ 12 =4 63 ÷ 7= 9 3 = 14 Use a strategy of your choice to solve these division problems. Show how you arrived at your answer. aThe 4 Herringer kids want to buy a Karaoke machine costing $192 for their mother’s birthday. Show how they could mentally work out each kid’s share of the cost. b85 swimmers are divided into 5 equal teams. How many swimmers in each team? $192 ÷ 4 85 ÷ 5 = 17 192 ÷ 2 = 96 Working out will vary. 96 ÷ 2 = 48 Working out will vary. Skills Not yet Kind of Got it • Uses knowledge of multiplication facts to solve division problems • Solves division problems using strategy of choice • Divides by tens, hundreds, thousands • Recognises and uses a range of mental division strategies halving split other • Applies strategies to real life problems 42 Series F Topic 2 Assessment Copyright © 3P Learning Written methods 1 Solve these written multiplication problems using a strategy of your choice: a 1 3 × b 2 2 × 4 2 × 3 6 c 5 4 e 6 3 × 0 × 5 f 8 4 1 8 × 3 7 Solve these written division problems: c b a 4 8 4 5 5 0 5 6 6 5 4 4 8 5 6 3 8 2 9 2 7 5 5 0 6 8 8 9 1 i h g 3 f e d 3 4 3 d 2 Name______________________ 9 9 2 You buy 7 train tickets at $65 each. How much have you spent? 3 Five DVDs cost $27. What is the cost of 1 DVD? Skills Not yet Kind of Got it • Solves 1 digit × 2 or 3 digit written multiplication problems • Solves written division problems with: no trading or remainders with remainders with trading and remainders • Chooses and uses correct process for solving real life problems Series F Topic 3 Assessment Copyright © 3P Learning 43 Written methods 1 Solve these written multiplication problems using a strategy of your choice: a 1 3 × b 2 2 × e 6 5 Methods will vary. c 5 4 1 4 2 2 × 9 d 6 8 8 3 6 3 × × 1 4 5 1 5 2 5 0 5 8 8 3 f 4 2 0 × 7 2 6 1 8 3 0 9 9 2 7 1 0 1 5 0 6 1 1 1 8 9 1 Solve these written division problems: a 4 d 6 2 1 8 4 1 0 6 5 g b 5 3 8 e r5 4 6 6 3 4 3 3 2 Name______________________ 3 2 h r4 2 9 1 0 1 5 0 5 1 2 1 4 8 5 1 0 2 9 2 3 You buy 7 train tickets at $65 each. How much have you spent? 3 $ 6 × 4 5 3 f r1 5 i r5 8 1 r1 r3 1 Five DVDs cost $27. What is the cost of 1 DVD? 5 $ 7 $ c 5 5 Skills 5 2 Not yet 7 4 2 0 0 0 Kind of Got it • Solves 1 digit × 2 or 3 digit written multiplication problems • Solves written division problems with: no trading or remainders with remainders with trading and remainders • Chooses and uses correct process for solving real life problems 44 Series F Topic 3 Assessment Copyright © 3P Learning Series F – Multiplication and Division Region Topic 1 Mental multiplication strategies Topic 2 Mental division strategies Topic 3 Written methods NS3.3 – selects and applies appropriate strategies for multiplication and division NSW • apply appropriate mental, written or calculator strategies to solve multiplication and division problems • recognise and use different notations to indicate division • record remainders as fractions and decimals when appropriate • multiply 3 digit numbers by one digit numbers using mental or written strategies • divide a number with 3 or more digits by a single digit divisor using mental or written strategies • use mental strategies to multiply or divide a number by multiples of ten • estimate answers to problems and check to justify solutions (WM) • select an appropriate operation and strategy for the solution of multiplication and division problems • question the meaning of packaging statements in best buy situations VELS Number – Level 4 VIC • • • • • • • e xplain and use mental and written algorithms for multiplication and division of whole numbers develop automatic recall of tables and understand factors and multiples establish equivalence relationships between mathematical expressions explain reasoning and procedures and interpret solutions understand factors and multiples use the mathematical structure of problems to choose strategies for solutions (WM) use estimates for computations and apply criteria to determine if estimates are reasonable or not (WM) • use inverse relations to validate calculations • identify calculation errors resulting in unreasonable results (WM) Level 4 QLD • w ork out multiplication and related division, applying number properties and mental computation strategies to larger numbers • use mental and written strategies to estimate and calculate a single operation • multiply and divide numbers by 10 and 100 mentally • know what factors and multiples are for 2 and 3 digit numbers • read and interpret practical problems, identify which operation/s to use, express it mathematically and then solve it, making sure their answer makes sense in the context • use a variety of methods including estimating and technology, to check for reasonableness of results (WM) Series F Outcomes Copyright © 3P Learning 45 Series F – Multiplication and Division Region Topic 1 Mental multiplication strategies Topic 2 Mental division strategies Topic 3 Written methods 3.8 SA • use a variety of estimation and calculating strategies including memorising multiplication and division facts Standards 3 - 4 TAS • r ecall automatically basic multiplication and division facts • use knowledge of place value and number properties to increase the range of problems that can be carried out mentally • use estimation to check the results of written calculations • analyse a problem that may involve different operations and choose the appropriate computational methods to solve it Level 4 WA/NT ACT 46 • understand the meaning, use and connections between operations and use this to choose and apply the correct operation • construct and completes statements • calculate with whole numbers (with multipliers and divisors to 10) drawing mainly on mental strategies • recognise, identify and use patterns involving operations 16.LC.16recall or use suitable strategies to work out multiplication and related division facts and apply facts to calculate mentally with larger numbers 16.LC.17use calculators to explore, develop and refine strategies for multiplication and division and for calculations using numbers beyond their mental scope 16.LC.18explain the calculation approaches they use, compare them with other approaches and check the reasonableness of their answers 16.LC.19apply number properties to modify calculations so that they can more easily be carried out (e.g. doubling, halving and bridging to the nearest decade number) and use inverse operations to solve relevant problems 16.LC.20choose when to use mental computation, written or electronic methods to calculate with numbers and form quick mental estimates to check calculations Series F Outcomes Copyright © 3P Learning
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