Name _______________________________ Date __________________ Teacher _______________
CODE
60105
Practice A
Choosing a Method of Computation
Answer the questions to describe the method of computation
you should use to solve each problem.
PROBLEM: In the 2002 Winter Olympic Games, the United States
won 10 gold medals, 13 silver medals, and 11 bronze medals. How
many medals did the United States win in all?
1. What method of computation will you use to solve this problem?
________________________________________________________________________________________
________________________________________________________________________________________
2. Why did you choose this method of computation?
________________________________________________________________________________________
________________________________________________________________________________________
3. What is the solution to the problem?
________________________________________________________________________________________
________________________________________________________________________________________
PROBLEM: The United States holds the record for the most
Summer Olympic Medals ever won. As of 2004, the United States
had won 850 gold medals, 661 silver medals, and 563 bronze
medals. How many Summer Olympic medals has the United States
won in all?
4. What method of computation will you use to solve this problem?
________________________________________________________________________________________
________________________________________________________________________________________
5. Why did you choose this method of computation?
________________________________________________________________________________________
________________________________________________________________________________________
6. What is the solution to the problem?
________________________________________________________________________________________
________________________________________________________________________________________
60105SR.doc
Name _______________________________ Date __________________ Teacher _______________
CODE
60105
Practice B
Choosing a Method of Computation
Choose a solution method and solve.
1. Athletes from 197 countries competed at the 1996 Summer
Olympic Games held in Atlanta, Georgia. That is 25 more
countries that competed at the 1992 games held in Barcelona,
Spain. How many different countries competed in Barcelona?
________________________________________________________________________________________
2. At the 1996 Summer Olympic Games held in Atlanta, Georgia,
10,310 athletes competed. At the 1992 Summer Olympic Games
held in Barcelona, Spain, 9,364 athletes competed. How many
more athletes competed in Atlanta than in Barcelona?
________________________________________________________________________________________
3. Marathon competitors run a total of 26 miles 385 yards. There
are 5,280 feet in a mile and 3 feet in a yard. How many yards
long is the entire marathon race?
________________________________________________________________________________________
4. The world record for the fastest men’s marathon race is 2 hours,
4 minutes, 42 seconds. The world record for the fastest
women’s marathon race is 2 hours, 15 minutes, 25 seconds.
How much faster is the men’s record marathon time?
________________________________________________________________________________________
5. The men’s outdoor world record in the high jump is 2.45 meters or
8 feet 0.5 inches. The women’s outdoor world record in the high
jump is 2.09 meters or 6 feet 10.25 inches. How much higher is
the men’s high jump record? Write the answer in meters and feet.
________________________________________________________________________________________
6. The men’s world record in the 400-meter relay is 37.40 seconds,
held by the U.S. If each of the four runners each ran 100 meters
in the same time, how long did each runner run?
________________________________________________________________________________________
7. The women’s world record for the fastest half marathon is 1 hour,
6 minutes, 25 seconds. How much faster is this than the
women’s world record for the fastest marathon (from exercise
4)?
________________________________________________________________________________________
60105SR.doc
Name _______________________________ Date __________________ Teacher _______________
CODE
60105
Practice C
Choosing a Method of Computation
Choose a solution method and solve.
The Paralympics are Olympics Games held for the disabled. The
Paralympics are held by the Olympic host country in the same year
and usually the same city. The XII Paralympic Summer Games were
held in Athens, Greece in 2004. The countries with the most medals
are as follows; China 141 (63 gold), Australia 100 (26 gold), and
Great Britain 94 (35 gold). Almost 4,000 athletes from 136 nations
competed in 19 sports.
1. How many gold medals did the top three countries with the most
medals win?
________________________________________________________________________________________
2. During the 2004 Summer Olympic Games, about 11,000 athletes
competed in 28 sports. About how many more athletes competed
in the 2004 Summer Olympic Games than in the 2004 Summer
Paralympic Games?
________________________________________________________________________________________
3. How many more medals did China win than Australia?
gold medals?
________________________________________________________________________________________
4. During the 2004 Summer Olympic Games, the U.S. won the
most medals with 103 medals (35 gold). Compare the country
with the most medals in the Summer Olympic Games with the
country with the most medals in the Summer Paralympic
Games. Which country had more medals? how many more?
how many more gold medals?
________________________________________________________________________________________
5. During the 2004 Summer Olympic Games, China won 63
medals (16 gold). How many medals in all did China take home
in 2004? gold medals?
________________________________________________________________________________________
6. During the 2004 Summer Olympic Games, Great Britain won
30 medals (9 gold). How many more medals in all did Great
Britain win in the 2004 Summer Paralympic Games than in the
Summer Olympic Games? gold medals?
________________________________________________________________________________________
60105SR.doc
Name _______________________________ Date __________________ Teacher _______________
CODE
60105
Review for Mastery
Choosing a Method of Computation
Paper and pencil, mental math, and a calculator are three
computation methods for solving problems.
• If there are many small numbers, use paper and pencil.
• If the numbers are small and easy, use mental math.
• If the numbers are large, use a calculator.
Before you solve a problem decide which computation method
is the best.
Choose a computation method. Then solve.
At a book fair, 76 books were sold on the first day and 82 books
were sold on the second day. How many books were sold during
the two days?
Number of books sold on the first day + Number of books sold on
the second day
76
+
82
The numbers are small and 82 is close to a multiple of 10. You can
use mental math.
(76 + 2) + (82 − 2) = 78 + 80 = 158
During the two days, 158 books were sold.
Choose a computation method. Then solve.
1. Of the 248 books on display, 46 were nonfiction books.
How many books were not nonfiction books?
________________________________________________________________________________________
2. Lisa bought 2 biographies for $5.37 each, a novel for $7.95,
and a bookmark for $1.19. How much money did Lisa spend?
________________________________________________________________________________________
3. Over two days, 234 students visited the book fair in groups
of 18. How many groups visited the fair?
________________________________________________________________________________________
60105SR.doc
Name _______________________________ Date __________________ Teacher _______________
CODE
Challenge
60105
Finger Math
Chisenbop is an ancient method of computation using your fingers.
One of the best-known forms of Chisenbop is used for basic
multiplication computations. It works only when all the factors
are greater than 5. Follow these steps to use this form of the
Chisenbop method of computation. The product of 6 ⋅ 7 is shown
as an example.
Step 1 Subtract 5 from the first factor.
Turn down that number of
fingers on your left hand.
Step 2 Subtract 5 from the second
factor. Turn down that number
of fingers on your right hand.
Step 3 Multiply the total number of
turned-down fingers on both
hands by 10.
Step 4 Find the product of the
numbers of fingers that are not
turned down on each hand.
Step 5 Add the two products from
Step 3 and Step 4.
3 ⋅ 10 = 30
↑
both hands
⋅
4
3 = 12
↑
↑
left hand
right hand
30 + 12 = 42
So, 6 ⋅ 7 = 42.
Use the Chisenbop method to find each product.
1. 7 ⋅ 8 = _______
2. 6 ⋅ 9 = _______
3. 8 ⋅ 6 = _______
4. 8 ⋅ 9 = _______
5. 6 ⋅ 6 = _______
6. 9 ⋅ 7 = _______
7. 7 ⋅ 7 = _______
8. 7 ⋅ 9 = _______
9. 8 ⋅ 8 = _______
10. 6 ⋅ 8 = _______
11. 9 ⋅ 9 = _______
12. 9 ⋅ 8 = _______
13. When would you choose to use the Chisenbop method
of computation? When would you choose not to use that
method? Explain.
________________________________________________________________________________________
________________________________________________________________________________________
________________________________________________________________________________________
Original content Copyright © by EduPro, Inc.
60105SR.doc
Name _______________________________ Date __________________ Teacher _______________
CODE
60105
Problem Solving
Choosing a Method of Computation
Use the table below to answer questions 1–6. For each question,
write the method of computation you should
use to solve it. Then write the solution.
Bones in the Human Body
1. How many bones are in an average
person’s arms and hands
altogether?
_______________________________________
2. How many more bones are in an
average person’s head than chest?
_______________________________________
3. Which part of the body has twice as
many bones as the spine?
_______________________________________
4. How many bones are in the body
altogether?
_______________________________________
5. A newborn baby has 350 bones.
How many more bones does a
newborn baby have than an adult?
_______________________________________
_______________________________________
Body Part
Head
Number of
Bones
28
Throat
1
Spine
26
Chest
25
Shoulders
4
Arms
6
Hands
54
Legs
10
Feet
52
6. How many bones are in each of an
average person’s feet, hands, legs,
and arms?
_______________________________________
_______________________________________
_______________________________________
_______________________________________
Choose the letter for the best answer.
7. The body’s longest bones—
thighbones and shinbones—are in
the legs. The average thighbone is
about 20 inches long, and the
average shinbone is about 17
inches long. What is the total length
of those four bones?
D calculator; 17 inches
8. The body has 650 muscles.
Seventeen of those muscles are
used to smile and 42 muscles are
used to frown. How many more
muscles are used to frown than
to smile?
A paper and pencil; 74 inches
B paper and pencil; 37 inches
F mental math; 35 muscles
C mental math; 20 inches
G mental math; 25 muscles
60105SR.doc
Name _______________________________ Date __________________ Teacher _______________
H paper and pencil; 608 muscles
J calculator; 633 muscles
CODE
60105
Puzzles, Twisters & Teasers
Crossword Mania
Complete the crossword puzzle.
Across
1. Good computation method to use to solve number 3 down.
3. The number of seconds in a week is how much greater than
604,780?
5. The number of months in a century is how many times greater
than the number of years in a century?
6. 121,780 is how many times greater than 12,178?
8. You can use this machine and the software that comes with it to
do complex calculations. It can even help people do their taxes.
9. The best calculating tool humans have; it helps you do mental
math.
Down
2. Good computation method to solve number 3 across.
3. A cheetah can run 60 miles an hour. If it could maintain that
speed for half an hour, how many miles could it run?
60105SR.doc
Name _______________________________ Date __________________ Teacher _______________
4. You can find the answer to number 5 across inside this.
7. 56 ⋅ 42 is how much less than 2,361?
CODE
60105
LESSON 1-5
Practice A
1. mental math
2. Possible answer: There are only 3
numbers to add. The numbers are
small and one is a multiple of 10.
3. The United States won 34 medals in all.
4. paper and pencil or calculator
5. Possible answer: The numbers are
too large to add mentally, and none of
the numbers are compatible.
6. The United States has won 2,074
Summer Olympic medals.
Practice B
1. Athletes from 172 countries competed
in Barcelona.
2. 946 more athletes competed in Atlanta.
3. The marathon is 46,145 yards long.
4. It is 10 minutes, 43 seconds faster.
5. 0.36 meters or 1 foot 2.25 inches.
6. 9.35 seconds.
7. 1 hour, 9 minutes faster.
Practice C
1.
2.
3.
4.
124 gold medals
about 7,000 more athletes
41 medals; 37 gold medals
China; 38 medals; 28 more gold
medals
5. 204 medals; 79 gold medals
6. 64 medals; 26 gold medals
Review for Mastery
1. mental math, 202 books
60105SR.doc
2. paper and pencil, $19.88
3. calculator, 13 groups
Challenge
1.
3.
5.
7.
9.
11.
13.
56
2. 54
48
4. 72
36
6. 63
49
8. 63
64
10. 48
81
12. 72
Possible answer: I would use this
method when both factors are greater
than 5 and less than 11. I would not
use this method when at least one of
the factors is less than or equal to 5.
Problem Solving
1.
2.
3.
4.
5.
6.
mental math; 60 bones
mental math; 3 bones
mental math; feet
paper and pencil; 206 bones
paper and pencil; 144 bones
paper and pencil; feet: 26 bones;
hands: 27 bones; legs: 5 bones;
arms: 3 bones
7. A
8. G
Reading Strategies
1. How many points has Marta earned?
2. Marta’s test scores: 85, 76, 88, 78,
and 91
3. Addition
4. 85 + 76 + 88 + 78 + 91 = 418 points
5. How much time does Marta spend
studying math in 5 days?
6. 35 minutes each night on math; 5
nights of studying
7. Multiplication
8. 5 ⋅ 35 = 175 minutes
Puzzles, Twisters and Teasers
Across
1. MENTALMATH
5. TWELVE
8. COMPUTER
Down
2. CALCULATOR
4. HEAD
60105SR.doc
3. TWENTY
6. TEN
9. BRAIN
3. THIRTY
7. NINE