Percentages — how to calculate a percentage step by step (Grade 7)
Every percentage problem links three quantities: the whole (the base = 100%), the rate (P, written as a percentage) and the part. To find the part, use the core formula part = whole · P ÷ 100. Worked example: 19% of 250 gives 47.5. Percentages suit Grade 7 / Year 8 maths.
Quick answer
Percentage maths links three quantities: the whole (the base = 100%), the rate (P%) and the part. To find the part, use part = whole · P ÷ 100. Example: 19% of 250 is 250 · 19 ÷ 100 = 47.5.
At a glance
| Example | 19% of 250 |
|---|---|
| Method | Core formula part = whole · P ÷ 100 |
| Steps | 4 |
| Answer | 47.5 |
| Check | 47.5 ÷ 250 · 100 = 19% ✓ |
| Grade level | Grade 6–7 (ages 11–13) |
Worked example: 19% of 250
The whole W = 250 and the rate P = 19% are given; the part is what we need to find.
Calculate a percentage — the 4 steps
These four steps work for any problem of the form “P% of the whole”.
Step 1 · Start
19% of 250Given: the whole 250 and the rate 19%.Step 2 · Formula
250 · 19 ÷ 100Whole times rate, divided by 100.Step 3 · ·
4750 ÷ 100First work out 250 · 19 = 4750.Step 4 · ÷100
= 47.5Dividing by 100 gives the part, 47.5.
Why the core formula works
Percent means “per hundred”: P% stands for P ÷ 100. Intuitively this is the unitary method — you scale the whole down to 1% (whole ÷ 100) and then up to P% (times P). From the single core equation part ÷ whole = P ÷ 100 you can rearrange to get all three basic tasks: the part, the rate and the whole.