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Fractions in Disguise

A comparison with a hundred underneath

A wall has 100 tiles. 37 are blue. That is 37 out of 100.

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A grid of 100 cells, none shaded.
Step 1 of 3
  1. A grid of 100 cells, none shaded.
  2. 37 cells shaded.
  3. 37 out of 100 is 37%.

The rule

Per cent means out of every 100. 37 out of 100 is written 37%. The second number is always 100.

Most counts are not out of 100. Multiply both numbers by one amount. Stop when the second reads 100. Because both are multiplied by one amount, the share does not change.

  • 9 out of 20: 9 × 5 = 45 and 20 × 5 = 100. That is 45 out of 100, or 45%.
  • 7 out of 50: 7 × 2 = 14 and 50 × 2 = 100. That is 14 out of 100, or 14%.

This works when the second number divides 100 exactly.

Jump to lesson

This track

  1. 0 Start here
  2. 1 A comparison with a hundred underneath
  3. 2 Three names for one amount
  4. 3 Taking a percentage of an amount
  5. 4 One amount said as a percentage of another
  6. 5 Measured against what you started with
  7. 6 An equal rise and fall do not cancel
  8. 7 Comparing two groups of different sizes
  9. 8 Where percentages are used
  10. 9 The big picture
  11. 10 Track quiz

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