How to Find a Percentage of a Number
Learn how to find a percentage of a number by converting percent to decimal, multiplying, checking answers, avoiding mistakes, and reading FAQs.
Quick Answer
To find a percentage of a number, convert the percent to a decimal by dividing by 100, then multiply by the number. For example, 20% of 50 is 0.20 x 50 = 10.
What You Need
- Percentage
- Original number
- Multiplication skills
- Calculator if needed
- Rounding rule if required
Safety Precautions
- Move the decimal two places left when converting percent to decimal.
- Check whether the question asks for the part, percent, or original number.
- Do not round too early in money or grade calculations.
- Use a calculator for important financial calculations.
Step-by-Step Instructions
- Step 1
Identify the percent
Find the percentage given in the problem.
- Step 2
Identify the number
Find the whole number the percent applies to.
- Step 3
Convert to decimal
Divide the percent by 100.
- Step 4
Multiply
Multiply the decimal by the number.
- Step 5
Label the answer
Use units such as dollars, points, or items if relevant.
- Step 6
Estimate to check
Compare with an easy percent like 10% or 50%.
- Step 7
Round if needed
Round according to the problem or context.
Practical Example
Example: To find 15% of 80, convert 15% to 0.15 and multiply 0.15 x 80 = 12.
Common Mistakes
- Multiplying by 15 instead of 0.15
- Moving decimal wrong direction
- Rounding too early
- Confusing percent increase with percent of a number
- Forgetting units
- Using the wrong original number
Troubleshooting
Answer seems too large
Check whether you converted the percent to a decimal.
Decimal conversion is confusing
Divide by 100 or move the decimal two places left.
Problem involves money
Keep extra decimals until the final cent rounding.
Need mental math
Find 10%, 5%, or 1% and combine them.
Helpful Internal Links
FAQs
What is 10% of a number?
Move the decimal one place left. For example, 10% of 80 is 8.
How do I find 25% quickly?
Find one quarter of the number, or divide by 4.
Is percent of the same as multiply?
Yes, after converting the percent to a decimal.
How do I check my answer?
Estimate with easy percentages and see if the result is reasonable.
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