Word problems with fractions, decimals and percentages
These stories use parts of a whole. Use the 4 steps: Understand, Plan, Solve, Check. Ask: is a fraction, a decimal or a percentage easiest here? "Of" usually means multiply.
Key idea / 要点
"½ of", "0.5 of" and "50% of" all mean the same: take half. Choose the form that makes the numbers easy.
A worked story
Worked example / 例题
A jug holds 2 L of juice. Mei drinks 25% of it. How much is left?
Plan: find 25%, then subtract.
25% of 2 L = 2 ÷ 4 = 0.5 L drunk.
Left = 2 − 0.5 = 1.5 L.
Check: 0.5 + 1.5 = 2 L. Correct!
Sharing with fractions
If ¾ of a 12 m rope is used, that is 12 ÷ 4 × 3 = 9 m. The rest is 12 − 9 = 3 m.
Remember / 记住
- "Of" means multiply.
- You can swap between fraction, decimal and percentage.
- Check that the parts add up to the whole.