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1.06 Calculations with decimals

Worksheet
Decimal calculations
1

Evaluate:

a

46.01 + 0.09

b

7.411 + 6.247

c

12.89 + 34.11

d

36.97 - 21.62

e

8.79 - 6.33

f

0.5 \times 1000

g

0.471 \times 5

h

2.2 \times 4

i

1.2 \times 3.2

j

4.23 \times 2

k

4.8 \times 8

l

2.68 \times 2.31

m

\dfrac{0.005\,34}{0.006}

n

\dfrac{0.247}{0.019}

o

9.2768 \div 2.08

p

56 \div 0.7

q

1.2 \div 0.3

r

420 \div 0.7

s

8.1 \div 0.9

t

393.68 \div 7

u

36.53 \times 63 \div 9

v

6.42 - 8.2 \times 0.7 + 4.67

2

Evaluate 2.270\,46 \div 0.474. Round your answer to two decimal places.

3

For the following expressions:

i

Estimate the answer by rounding both values to the nearest whole number.

ii

Find the answer using a calculator.

iii

Hence, find the difference between the estimate and the actual answer.

iv

Suggest a way to improve the accuracy of your estimate.

a

6.61 + 2.85

b

9.66 - 7.88

c

11.59 \div 4.44

4

For each of the following expressions:

i

Estimate the answer by rounding both values to the nearest whole number.

ii

Find the answer using a calculator. Round your answer to two decimal places.

a

1.29 \times 3.42

b

26.99 \div 8.98

Applications
5

A calculator is 8.9\text{ cm} long. How far will 130 calculators reach if laid end to end? Give your answer in metres.

6

How many pieces of steel, each 4.25\text{ m} long, can be cut from a wire 153\text{ m} long?

7

A piece of cord 2.87\text{ m} long is cut evenly into smaller pieces of 0.07\text{ m} each. How many of these pieces can be cut?

8

Dave used a calculator to evaluate 6.573 \times 8.03 but forgot to enter the decimal points. The answer he got was 5\,278\,119. What should the answer have been?

9

Maria runs 50.2 \text{ m} in 15 seconds. If she continues running at the same speed, how far can she run in 2 minutes?

10

Sebastian owes \$47.59 to each of his 3 friends. How much money does he owe altogether?

11

Three items weighing 3.41\text{ kg}, 2.58\text{ kg} and 5.79\text{ kg} are to be posted but are too heavy to send. By how much does the total weight exceed the 11.38\text{ kg} limit?

12

At 10 pm, the temperature in Victoria is 16.7\degree \text{C}. Each hour the temperature decreases by 1.87\degree\text{C}. What is the temperature 5 hours later?

13

Christa is creating a 3-minute slide show with pictures from her holiday. Each picture will be displayed for 4.5 seconds.

a

How many seconds are in 3 minutes?

b

How many pictures can she show in 3 minutes?

14

Brad is currently \$18 overdrawn in his account. He knows that he needs to pay a \$61.61 bill from this account tomorrow. How much does he need to add to this account so he can pay his bill tomorrow?

15

A diver is 3.5 metres below the surface of the water. He descends 1.47 metres each second for 3 seconds, then rises 0.46 metres/second for 6 seconds. The level at the surface is 0 metres, and 1 metre below is represented by - 1 metres.

a

Find the depth of the diver after 9 seconds.

b

The diver sees a turtle near the surface and needs to get to a depth of 0.35 metres below the surface within 4 seconds to snap the perfect shot. How many metres does he need to rise each second, assuming he will rise at a constant speed?

16

Mae earns \$36.43 per hour working as a call center operator. If she works 20.5 hours per week, find her weekly wage.

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Outcomes

1.1.2

check results of calculations for accuracy

1.1.6

choose and use addition, subtraction, multiplication and division, or combinations of these operations, to solve practical problems

1.1.7

apply arithmetic operations according to their correct order

1.1.9

evaluate fractions and decimals of quantities to the required number of decimal places; for example, 3/4 of 250 ml, 0.4 of 3kg

1.1.12

use a calculator appropriately and efficiently for multi-step calculations

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