Double, then divide by 10
How to divide by 5 mentally
Dividing by 5 is equivalent to multiplying by 2 and dividing by 10. Doubling is usually simple, and the final division only moves the decimal point one place to the left.
The pattern
n ÷ 5 = (n × 2) ÷ 10
Step by step
- 1Double the number being divided.
- 2Divide that result by 10.
- 3Keep the decimal when the division is not a whole number.
Worked examples
85 ÷ 5
170 ÷ 10
17
240 ÷ 5
480 ÷ 10
48
37 ÷ 5
74 ÷ 10
7.4
This method works for whole numbers and decimals. When doubling a decimal is easier than doing long division, it is often the quickest route.
Try the pattern
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