Chapter 7 Decimals Worksheet - New Century Maths Page 25
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383 Find:
a 0.651 ÷ 3
b 37 ÷ 8
c 0.078 ÷ 6
d 675 ÷ 12
e 89.341 ÷ 7
f 4.275 ÷ 5
g 2.75 ÷ 4
h 0.093 ÷ 11
117.44 ÷ 16
i
j 79.86 ÷ 33
k 31.98 ÷ 13
130.76 ÷ 28
l
m 0.471 ÷ 3
n 256.84 ÷ 4
o 0.696 ÷ 12
Dividing decimals by decimals
Look at this pattern:
18 ÷ 3 = 6
180 ÷ 30 = 6
1800 ÷ 300 = 6
When dividing two numbers, if we multiply both numbers by the same power of 10 first, the
answer stays the same. We can use this property to help us divide decimals. For example:
9.8 ÷ 0.08 = 980 ÷ 8
(multiplying both numbers by 100)
= 122.5
The answer to 980 ÷ 8 is easier to find because it involves division by a whole number.
To divide a decimal by a decimal:
Step 1: Make the second decimal a whole number by moving the decimal point the
appropriate number of places to the right.
Step 2: Move the decimal point in the first decimal the same number of places to
the right.
Step 3: Divide the new first number by the new second number.
This works because in Steps 1 and 2 we multiply both decimals by the same power of 10.
Example 17
Animation
7-02
Evaluate each of the following:
Dividing
a 0.4 ÷ 0.2
b 1.75 ÷ 0.5
c 122.4 ÷ 7.65
decimals
Solution
a 0.4 ÷ 0.2
Move the decimal points one place to the right (multiplying both decimals by 10).
= 4 ÷ 2 = 2
b 1.75 ÷ 0.5
Move the decimal points one place to the right (multiplying both decimals by 10).
= 17.5 ÷ 5 = 3.5
c 122.4 ÷ 7.65
Move the decimal points two places to the right (multiplying both decimals by 100).
= 12 240 ÷ 765 = 16
Always check by estimation that your answers sound reasonable.
222
NEW CENTURY MATHS 7
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