Percentages Made Easy

What is a percentage?

The word percent means "out of 100". The symbol is %.

So 50% means 50 out of 100, which is the same as one half. If a test is marked 90%, you got 90 out of every 100 marks.

Thinking of percentages as "out of 100" makes them easy to picture: imagine a grid of 100 squares and colour in the percent you need.

Percentages, fractions and decimals

These three are just different costumes for the same value. To switch between them:

• Percent → decimal: divide by 100 (move the point two places left). 35% → 0.35
• Percent → fraction: write it over 100 and simplify. 40% → 40/100 → 2/5

Percent	Decimal	Fraction
10%	0.1	1/10
25%	0.25	1/4
50%	0.5	1/2
75%	0.75	3/4
100%	1.0	1 (a whole)

If the fraction part feels shaky, review introduction to fractions first.

Finding a percent of a number

The reliable method: turn the percent into a decimal, then multiply.

Worked example: What is 25% of 80?

1. 25% = 0.25
2. 0.25 × 80 = 20

Worked example: What is 30% of 150?

1. 30% = 0.30
2. 0.30 × 150 = 45

Handy mental shortcuts

You do not always need a calculator. Build answers from easy percentages:

• 10% → divide by 10
• 1% → divide by 100
• 50% → halve the number
• 5% → half of 10%
• 25% → halve, then halve again

Example: 35% of 200

• 10% of 200 = 20, so 30% = 60
• 5% of 200 = 10
• 35% = 60 + 10 = 70

Percentage increase and decrease

Decrease (a discount): find the percent, then subtract.

A $40 jacket is reduced by 10%.

• 10% of 40 = 4
• New price = 40 − 4 = $36

Increase (like a tip or tax): find the percent, then add.

A $50 bill gets a 20% tip.

• 20% of 50 = 10
• Total = 50 + 10 = $60

Finding what percentage one number is of another

To find what percent A is of B, divide A by B and multiply by 100.

You scored 18 out of 24 on a quiz. What percent is that?

• 18 ÷ 24 = 0.75
• 0.75 × 100 = 75%

Why percentages matter

Percentages are everywhere in real life: sales, taxes, tips, battery levels and test scores. Once you connect them to decimals and fractions, you can handle almost any percentage problem. To keep building your number skills, try algebra basics next.