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← Fractions in Disguise

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Lesson 3 of 11

Taking a percentage of an amount

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6 min

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A hall has 250 chairs. 40% are booked. You want a count, not a percentage.

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Cut the amount into a hundred equal strips.
Step 1 of 3
  1. Cut the amount into a hundred equal strips.
  2. One hundredth (1%) is 2.5.
  3. Take 40 of them: 40% is 100.

The rule

The word of means times. To take a percentage of an amount, find pieces and add them.

  • 10% is one tenth of the amount.
  • 5% is half of 10%.
  • 15% is 10% plus 5%.

10% is one tenth because 10 is one tenth of 100.

For any percentage, divide the amount by 100. The result is 1% of the amount, because 1% is one hundredth. Then multiply by the number before the % sign.

  • 40% of 250 chairs: 250 ÷ 100 = 2.5. Then 2.5 × 40 = 100 chairs.
  • 15% of 200: 10% is 200 ÷ 10 = 20. 5% is half of 20, which is 10. So 15% is 20 + 10 = 30.
  • 8% of 450: 450 ÷ 100 = 4.5. Then 4.5 × 8 = 36.

Try the lab to finish this lesson.