April 13, 2023

Negative numbers and decimals

2. Multiplying and dividing decimals

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April 13, 2023

thou

sand

ths

× 10÷ 10

× 100

hu

nd

red

s

ten

s

on

es

ten

ths

hund

redt

hs

When you multiply a decimal by 10, or a multiple of 10, the digits all move to the left, according to how many “0”s there are.

166× 10The decimal point stays put.

When dividing by a multiple of 10, each digit moves to the right, according to how many “0”s there are.

2 9

If the digits all move beyond the decimal

0

As it is easier, we actually move just the decimal point, but remember that this represents moving all the digits the other way.

point, you must write a zero in the “ones” column.

÷ 10 0

0

Explanation

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April 13, 2023

3.92 × 100

22.4 ÷ 100

0.83 × 10

14.7 ÷ 10

0.02 × 1000

8,390 ÷ 1000

392

0.224

8.3

1.47

20

8.39

Practise

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April 13, 2023

×

Multiplying two decimal numbers.

3.24 2.3First, ignore the decimal points.

×3.24 2.3Multiply.

Count and total the number of digits after both decimal points, in the original calculation.

The decimal point should have this number of digits after it, in you answer.

= 7452

123

452.7

Explanation

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April 13, 2023

3.92 × 2.2

22.4 × 1.37

0.83 × 2.96

14.7 × 3.745

0.02 × 16.8

11.66 × 4.853

8.624

30.688

2.4568

55.0515

0.336

56.58598

Practise

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April 13, 2023

2.42.4

24

3.24 ÷

Dividing two decimal numbers.

First, write the division as a fraction.

Multiply both the denominator and the numerator by 10, or 100 or any other power of 10, so that the denominator is a whole number.

3.24 ÷3.2

.4

If you can, cancel , then divide as normal.

32.4 0241.35

8 12

Explanation

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April 13, 2023

3.12 ÷ 2.4

7.02 ÷ 1.3

2.728 ÷ 0.88

23.836 ÷ 5.7

0.03 ÷ 0.025

114.75 ÷ 4.25

1.3

5.4

3.1

4.18

8.5

27

Practise

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