Per cent means out of 100. 40% means 40 out of every 100, which is 40/100 or 0.4. To find a percentage of an amount, you can use easy facts. 10% is one tenth, so divide by 10. 50% is half and 25% is a quarter.
Build other percentages from these. To find 30% of 170, find 10%: 17. Then multiply by 3: 51. To find 5%, halve 10%. You can also multiply by the decimal: 30% of 170 = 0.3 × 170 = 51.
Worked example
Find 35% of 80.
- 10% of 80 is 8, so 30% is 24.
- 5% is half of 10%: 4. Add: 24 + 4 = 28.
Answer:28
Key words
- percent (%)
- out of one hundred
- 10%
- one tenth
- decimal multiplier
- the percentage written as a decimal, like 0.35
Practise this
New questions every time.
Common Core-referenced: 6.RP.A.3c