Use the part-to-whole ratio as a cross-check
13:20 simplifies to 13:20. Reading that reduced ratio as a decimal and multiplying by 100 gives the same percentage, which is a useful check on the direct formula.
- 1.Form the ratio 13 ÷ 20.
- 2.13 ÷ 20 = 0.65.
- 3.0.65 × 100 = 65%.