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Decimals are my thingYou see them all aroundTemperature, time, receipts and billsThey're even in the pound!

Can you think of any more examples?

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DECIMALS

DECIMALS

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PLACE VALUE

Hundreds100s

Tens10s

Units1s

. Tenths10ths

Hundredths100ths

Thousandths1000ths

1 4 . 1 3

7 . 5 0 9

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MULTIPLYING BY 10, 100 ,1000

0 x 10 x100 x 1000

22.0 220 2200 22000

16.5 165 1650 16500

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DIVIDING BY 10, 100 ,1000

÷ 10 ÷ 100 ÷ 1000

19500 1950 195 19.5

234 23.4 2.34 0.234

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ADDITION AND SUBTRACTION

• LINE UP DECIMAL POINTS EXACTLY• ADD OR SUBTRACT THE SUM

E.g. 2.34 + 18.034 and 234 – 3.56

18.034 234 +2.34 - 3.56

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MULTIPLICATION

• 3.45 x 2.1• Ignore the decimal points• Multiply as normal• Put the decimal point back into the answer

345 x21

Put the decimal point back into the answer. Look at the question, there are 3 numbers after the decimal place so work the decimal place back into the answer.

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Division

• To divide a whole number into a decimal • Divide as normal • Keep the decimal points in line• Round the answer to sensible number of figures

where necessary

E.g. 172.6 ÷ 4Keep the decimal points in line

4 Add 0s to the end if need be

Note – check by multiplication

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Divide a decimal by a decimal

• Change the number you are dividing by into a whole number.

• Do this by multiplying by 10, 100, 1000

• Do exactly the same to the number you are dividing

• Divide to find the answer

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continued

E.g. 7.4 ÷ 0.05

Multiply the 0.05 by 100 to make it into a wholeNumber. Then do the same to 7.4. 5

Check by multiplication – 148 x 0.05 = 7.4

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continued• Find 31.52 ÷2.4Multiply 2.4 x 10 = 24Multiply 31.52 x 10 = 315.2 2 4 3 1 5 . 2

= 13.133333333333333333333333

So we round to 13.13 (to 2 dp)