← Maths topics
Percentages
What a percentage really means
Per cent means 'out of 100'. So 35% means 35 out of every 100. To work with a percentage you turn it into a number you can multiply by: divide by 100. 35% becomes 0.35.
Finding a percentage of an amount
Multiply the amount by the decimal. 35% of 80 is 0.35 x 80. That is one multiplication — no need to find 10% and add pieces unless you prefer it.
Increase and decrease
An increase of 20% means you end with 100% + 20% = 120%, so multiply by 1.2. A decrease of 20% means you end with 100% - 20% = 80%, so multiply by 0.8. Find the multiplier first, then multiply once.
Worked example
A coat costs £60. In a sale it is reduced by 15%. What is the sale price?
- 1First check what's being asked: the price after the reduction, not the size of the reduction.
- 2Decide the multiplier: 100% - 15% = 85%, so the multiplier is 0.85.
- 3Multiply once: 60 x 0.85.
- 4Write the answer in context, with units: £51.
Answer: £51