What is a percentage?
A percentage means "out of 100". The sign is %. So 25% means 25 out of 100, which is the same as the fraction 25/100 = 1/4, or the decimal 0.25.
Key idea / 要点
To find a percentage of an amount, change the % to a fraction over 100, then multiply: p% of N = (p ÷ 100) × N.
Finding a percentage
Worked example / 例题
Find 25% of 80.
25% = 25/100 = 1/4.
1/4 of 80 = 80 ÷ 4 = 20.
So 25% of 80 is 20.
Useful percentages
Some are easy to remember: 50% = ½, 25% = ¼, 10% = 1/10, and 100% means the whole thing. For example, 10% of 60 is 60 ÷ 10 = 6, and 50% of 60 is 60 ÷ 2 = 30. Knowing these makes shopping discounts much easier to work out.
Remember / 记住
- Percent means "out of 100".
- 10% of a number = divide by 10.
- 50% = half, 25% = a quarter.