Before you dive into price changes, discounts, tax and interest, refresh the three core computations from grade 6.
Three core computations
| if you want | and you know | method |
| the part | whole and percent | `whole × percent ÷ 100` |
| the whole | part and percent | `part × 100 ÷ percent` |
| the percent | part and whole | `part × 100 ÷ whole` |
Mental shortcuts
- 10 % of a number — divide by 10 (shift the decimal one place left).
- 25 % = `1/4`, 50 % = `1/2`, 75 % = `3/4`.
- 20 % = twice 10 %, 5 % = half of 10 %.
Practice examples
- What is 25 % of 80? → `80 ÷ 4 = 20`.
- What is 30 % of 60? → `10 % = 6`, `30 % = 18`.
- The part is 12 and it represents 25 % — what is the whole? → `12 × 4 = 48`.
Next in grade 7
You are ready for the more advanced tasks: