Work through the examples below, then open Percentage Calculator to check your own numbers and practice the skill.
What does percent mean?
Percent means “out of one hundred.” A percentage compares a part with a reference whole. For example, 25% of a class means 25 out of every 100 students if the class were scaled to 100 students.
Write the percentage sign immediately after the number, but pronounce it as a separate word: 8% is “eight percent,” not “eight per cent of nothing.” When stating a result, name the whole: “Eight percent of the budget was spent.”
How to pronounce common percentages
| Written | Spoken | Decimal form |
|---|---|---|
| 5% | Five percent | 0.05 |
| 12.5% | Twelve point five percent | 0.125 |
| 0.5% | Zero point five percent | 0.005 |
| 0.05% | Zero point zero five percent | 0.0005 |
| 150% | One hundred fifty percent | 1.5 |
Notice that 0.5% and 0.05% are different. Reading each decimal digit prevents tenfold errors.
Reading percentage increases and decreases
Be explicit about the starting value. “The price increased by 20%” means the new price is 120% of the original; it does not mean the new price is 20%.
For a $80 item, a 20% increase adds $16 and gives $96. A 20% decrease from $80 removes $16 and gives $64. An increase of 20% followed by a decrease of 20% does not return to the start: $80 → $96 → $76.80.
Percentage points are different from percentage changes. Moving from 10% to 15% is a rise of 5 percentage points, but a relative increase of 50%.
From percent to decimal and back
To convert a percentage to a decimal, divide its number by 100: 2.5% = 0.025. To convert a decimal to a percentage, multiply by 100: 0.375 = 37.5%.
To find 30% of 250, calculate 250 × 0.30 = 75. When entering a percentage on a calculator, check whether its % key applies the percentage to the preceding amount for addition and subtraction, because calculator conventions can differ.
Practice reading and calculating percentages
Say these figures aloud before looking at the answers: 7.25%, 0.08%, and 200%. Then calculate 15% of 120.
Answers: “Seven point two five percent,” “zero point zero eight percent,” and “two hundred percent.” For the calculation, 120 × 0.15 = 18. Use the linked Percentage Calculator to check another amount.
Common percentage mistakes
Avoid confusing 0.5 with 0.5%: 0.5 is 50%, while 0.5% is 0.005. Avoid saying a 5-percentage-point rise is necessarily a 5% increase. And when a percentage exceeds 100%, remember it is comparing a quantity larger than the chosen whole—not necessarily a bad calculation.
Frequently asked questions
How do you say 0.5%?
Say “zero point five percent” or “half a percent.” It equals 0.005 as a decimal.
Is 100% the same as 1?
Yes. In decimal form, 100% is 1, or one whole.
How do you read 150%?
Say “one hundred fifty percent.” It means one and a half times the reference amount.
Use Percentage Calculator to verify a new example, then try the related practice activities.