Learning percentages — calculating percent
"Percentages make fractions of 100 visible: 50 % is half, 25 % a quarter. Once you see the link between percent, fractions and decimals, discounts, grades and statistics become child’s play."
What is this topic about?
Per cent means “per hundred”: 40 % is 40 out of 100, so 40/100 = 0.4. The core tool is the percentage formula (percentage = base × rate ÷ 100) plus its two siblings for base and rate. In grades 5–6 percentages grow from simple shares (50 %, 25 %, 10 %) to discounts, VAT and interest; grade 7 adds percentage points and growth factors (increase by 20 % = × 1.2). Mental paths: 10 % = divide by 10, 5 % = half of 10 %, 1 % = divide by 100.
The best way to learn it
Break rates apart: 35 % = 25 % + 10 % (a quarter plus a tenth).
10 % is just “divide by 10” — build every percentage from tens and ones.
Growth factors bundle steps: +20 % then −20 % is ×1.2×0.8 = ×0.96 — not back to the start.
Frequently asked questions
Practise percentages in a duel
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