How to find a percentage of a number
“20 percent of 150” asks for 20 of every 100 parts of the whole. Turn the percentage into a decimal share, then take that share of the whole value.
What the formula is saying
Percent means divided by 100. Thus 20% = 0.20, and multiplying the whole by 0.20 finds the requested part.
Read the symbols in plain language
- p
- Percentage%
- total
- Whole valueSame unit as the whole
Sort out the units first
Enter 20 in the percentage field to request 20%, not 0.20. The answer has the same quantity unit as the whole, such as points or metres.
Let’s solve one together
Read the given values, follow each operation, then check what the result means.
- p · Percentage
- 20 %
- total · Whole value
- 150
Turn the percent into a decimal share
Dividing by 100 gives the fraction of the whole to take.
(20) ÷ 100 = 0.2Multiply by the whole value
Take that fraction of the entire amount.
(0.2) × (150) = 30
Does this worked answer make sense?
10% of 150 is 15, so 20% is twice that: 30. At 100%, the answer must equal the whole.
Now try your own values
Change a value or its unit. The same method will show your calculation, step by step.
Results update only when you calculate. The lesson example above stays unchanged.
Your turn — check your understanding
Use these new values. Work it out first, then check your answer.
- p · Percentage
- 15 %
- total · Whole value
- 240
Find: a percentage of a number
A hint, not the answer
Percent means divided by 100. Thus 20% = 0.20, and multiplying the whole by 0.20 finds the requested part.
Enter 20 in the percentage field to request 20%, not 0.20. The answer has the same quantity unit as the whole, such as points or metres.
Show the full practice solution
Compare the steps with your work; revealing a solution does not mark the lesson complete.
Turn the percent into a decimal share
Dividing by 100 gives the fraction of the whole to take.
(15) ÷ 100 = 0.15Multiply by the whole value
Take that fraction of the entire amount.
(0.15) × (240) = 36
Avoid the common trap
Do not divide by 100 twice. A discount amount is not the final price; subtract the discount from the original price in a separate step.
When this method applies — and when it does not
Nonnegative percentages and whole values. Percentages above 100 are permitted and represent more than the whole.
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Sources & further reading
References open in a new tab and explain the underlying principles. The teaching text and examples here are SimpleFlick’s own; the source organisations have not endorsed this calculator.
Lesson updated: · Worked examples checked against the implemented formula; not an independent engineering certification.