Page 42 - Mathematics Coursebook

3.7 Dividing decimals

3.7 Dividing decimals

When you divide a decimal number by a single-digit number:
t use short division
t keep the decimal point in the question and write the decimal
point in the answer above the decimal point in the question.

Worked example 3.7
Work these out. a 4.86 ÷ 2 b 29.35 ÷ 5

a 2 First of all work out 4 ÷ 2 = 2. Write the 2 above the 4.
) 24 86.
2 Now write the decimal point in the answer.
) 24 86.
24 3 Now work out 8 ÷ 2 = 4 and write the answer above the 8.
.
) 24 86 Finally work out 6 ÷ 2 = 3 and write the answer above the 6.
.
b 5 First, try to work out 2 ÷ 5. You can’t do it, so work out 29 ÷ 5 = 5 remainder 4.
) 52 9 . 4 3 5 Write the 5 above the 9 and carry the 4 across to before the 3.

5 . Now write the decimal point in the answer.
) 52 9 . 4 3 5

5 .8 Now work out 43 ÷ 5 = 8 remainder 3.
4
3
) 52 9 . 4 3 5 Write the 8 above the 3 and carry the 3 across to before the 5.
5 .8 7 Now work out 35 ÷ 5 = 7.
3
) 52 9 . 4 3 5 Write the 7 above the 5.
3

) Exercise 3.7

1 Work these out.
a 6.3 ÷ 3 b 4.6 ÷ 2 c 4.9 ÷ 7 d 8.4 ÷ 3 e 9.1 ÷ 7

2 Work these out.
a 8.26 ÷ 2 b 6.93 ÷ 3 c 4.84 ÷ 4 d 18.66 ÷ 6 e 45.05 ÷ 5

3 Shen sees this sign in a supermarket.
What is the cost of one chicken? 5 chickens for $18.25

4 Maggie pays $9.28 for 8 m of ribbon.
What is the cost of the ribbon per metre?

5 Copy and complete these divisions.

a . 1 b 2 . 5 c 5 . 9
2 6 ) . 1 8 3) . 1 9 3 ) 5 . 5 3

3 Place value, ordering and rounding 41