How_To_Be_Good_At_Math

150 CALCULATING •^ DIVIDING WITH DECIMALS

Dividing with decimals

Dividing a number by a decimal number or dividing a decimal number

is simple if you know how to divide whole numbers and how to multiply

numbers by multiples of 10 (see pages 108-109).

Let’s divide 536 by 0.8

First, multiply both the divisor and the

dividend by 10. Then 536 becomes

5360 and, 0.8 becomes 8.

536 ÷ 0.8 =?

Multiply both the dividend and

divisor by 10 until the decimal

number you’re working with

becomes a whole number.

You’ll need four

place-value

columns for this

calculation

−

8

Th H T O

5 3 6 0

(^48)
(^56)
6
Now carry out a division
calculation. We can see from the
completed calculation shown here that
5360 ÷ 8 = 670
(^70)
So, the answer to 536 ÷ 0.8 = 670 and 5360 ÷ 8 = 670
both 536 ÷ 0.8 and
5360 ÷ 8 is 670.
Dividing by a decimal
When a divisor (the number you’re dividing by) is a decimal
number, first multiply it by 10 as many times as it takes to give
you a whole number. You also have to multiply the dividend (the
number being divided) by 10 the same number of times. Then
do the division calculation and the answer will be the same
as it would if you did the calculation without multiplying first.
536 × 10 = 5360
0.8 × 10 = 8
150_151_Dividing_using_decimals.indd 150 29/02/2016 19:04