U3L4 Green - Multiply Decimals With Decimals
In each question, round your answer sensibly.
1. The price ticket on a packet of meat gives the weight (1.455 kg), and the price per
kg ($7.99). What is the price of the meat?
2. Calculate the cost of buying 1.14 kg of capsicums at $5.39 a kg. Remember that
stores will always “round up” prices to the next highest cent.
3. Chocolate bars are sold at a dairy for 95¢ each. In one week period the dairy sells
320 bars. How much would 320 bars cost?
4. The materials needed to construct a fence are 8 posts which cost $9.25 each, 14
railings at $4.75 each and 70 palings at $2.80 each. What is the total cost of the
fence?
5. A bike store requires a deposit of $107 and 18 monthly payments of $35.50. What is
the total cost of the bike?
6. A drilling rig drills on average 4.3 m in an hour. The rig is operational 8 hours a day
for 7 days of the week. How far will it drill in one week?
7. To hire a car costs $57 dollars a day plus 37¢ per km travelled. A tourist hires a car
for 8 days and travels 1452 km. What is the total cost of hiring the car?
8. Carpeting costs $7.99 per yard. If Jan buys 12.4 yards, how much will it cost her?
(Remember that money is always rounded to the nearest hundredth)
9. These numbers have been multiplied on a broken calculator. The decimal point and
the zeros at the front are not showing up.
Write the number in the Display column as it should appear.
a.
b.
c.
d.
First number
0.4
0.01
8
0.04
x
x
x
x
Second number
0.3
14.3
168
0.05
=
=
=
=
Display
12
143
1344
2
Correct answer
10. Complete this table. Do the multiplication without using a calculator.
x
0.3
0.08
0.12
0.2
4
0.05
1.2
0.144
11. If Joe rides his bike at 12.7 mph, how far will he go in 3.2 hours?
12. Jay’s car uses a gallon of gas for every 17.5 miles he drives. If he bought 13.5 gallons
of gas, how many miles could he travel?
13. David bought Toblerone chocolates for his grandmother. He bought 2.5 pounds at a
cost of $3.80 per pound. How much did he pay for the chocolates?
14. The formula for the area of a circle is A = πr2. If the measurement of the circle’s
radius is 2.5 cm, and the value of π = 3.14, find the circle’s area.
15. Which is the better buy: A six pack of 333 ml cans of soda at 45 cents each, or a 1.5
liter plastic bottle of cola at $2.50?
16. Shane is buying some food from a dairy. Here's the printout from the register
Avocado 5 @ 1.95 each
Cheese
Ramen noodles
Coffee
Total
9.75
4.85
3.25
8.75
26.60
Shane spots two mistakes. The sign for avocado says $1.65 each. The shop assistant
has mixed up the digits for Ramen noodles. It should cost $2.35.
Calculate how much Shane has been overcharged.
17. The total height of Jim and Irene is 2.98 m. The total height of Irene and Mark is
2.94 m. If Mark is 0.02 m taller than Irene, how much taller is Jim than Mark?
18. On a field trip, the school minibus uses 10.4 liters of gasoline, which costs $0.95 per
liter. If maintenance costs are $0.45/km, what is the total cost for the 183 km trip?
19. Farmer Phil wants to spread fertilizer on his 3.62 hectare (Ha) farm at a rate of 2.3
kg per hectare. Fertilizer costs $99.50 for a 10 kg bag, $51.40 for a 5 kg bag,
$23.60 for a 2 kg bag and $13.60 for a 1 kg bag. What is the cheapest cost of
fertilizing this farm, keeping in mind that he can only buy whole bags of fertilizer?
Solutions
1. $11.63
2. $6.15
3. $304
4. $336.50
5. $746
6. 240.8 meters
7. $993.24
8. $99.08
9.
a.
b.
c.
d.
10.
First number
0.4
0.01
8
0.04
x
0.3
0.08
0.12
0.2
0.06
0.016
0.024
x
x
x
x
4
1.2
0.32
0.48
Second number
0.3
14.3
168
0.05
0.05
0.015
0.004
0.006
=
=
=
=
Display
12
143
1344
2
Correct answer
0.12
0.143
1344
0.0002
1.2
0.36
0.096
0.144
11. 40.64 miles
12. 236.25 miles
13. $9.50
14. 19.625 cm2
15. The six pack
16. $2.40
17. Mark = 1.48 m, Jim = 1.52m, Irene = 1.46 m
18. $82.35 + $9.88 = $92.23
19. 8.326 kg of fertilizer are needed.
The cheapest cost is to buy one 5 kg bag and two 2 kg bags for $98.60.
Bibliography Information
Teachers attempted to cite the sources for the problems included in this problem set. In some cases,
sources may not have been known.
Problems
Bibliography Information
1-16 (mixture)
Barton, David. Alpha Mathematics. Auckland:
Longman.
1-16 (mixture)
Barton, David. Alpha Mathematics Homework
Book. Longman. ISBN 0 582 54260 X. Pearson
Education New Zealand, 2000.
1-16 (mixture)
Barton, David. Beta Mathematics. Pearson
Education New Zealand.
1-16 (mixture)
Barton, David. Beta Mathematics Homework
Book. ISBN 978-1-4425-0017-4. Pearson
Education New Zealand, 2000.