Lesson 1 of 11
A comparison with a hundred underneath
Show on a big screenA wall has 100 tiles. 37 are blue. That is 37 out of 100.
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Step 1 of 3
- A grid of 100 cells, none shaded.
- 37 cells shaded.
- 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.
Try the lab to finish this lesson.