Fractions, decimals & percentages
Three ways to write the same part of a whole — and how to switch between them.
0.5, 1/2, and 50% are three costumes for the same number. Knowing how to swap between them is one of the most useful arithmetic skills you can carry.
Fractions, decimals, and percentages are three ways of writing the same family of values. Each form is best for a different job.
Discounts, tips, recipes, sport stats, scientific data — switching between FDP fluently saves time and avoids misreadings.
Convert between forms
- Fraction → decimal: divide top by bottom. 3/4 → 3 ÷ 4 = 0.75
- Decimal → percent: × 100. 0.75 → 75%
- Percent → fraction: put over 100, simplify. 25% = 25/100 = 1/4
Express 3/8 as a percentage.
Which is bigger: 2/3 or 65%?
2/3 ≈ 66.67%. So 2/3 > 65%.
Don't move decimals from fraction → percent. You must divide first. 1/2 isn't 12% — it's 50%.
Memorise: 1/2 = 50%, 1/4 = 25%, 1/3 ≈ 33.3%, 1/5 = 20%, 1/8 = 12.5%, 1/10 = 10%. Covers most everyday cases.
- FDP = three notations for the same value.
- Fraction → decimal: divide. Decimal → %: ×100.
- Memorise the common ones to spot conversions instantly.