Percentages compare values on a scale of one hundred. The main challenge is identifying whether the task asks for a percentage of one number, a final amount after a change or the percentage difference between an old and new value.
By Calqoras Editorial Team • Reviewed September 1, 2026
Percentages compare values on a scale of one hundred. The main challenge is identifying whether the task asks for a percentage of one number, a final amount after a change or the percentage difference between an old and new value.
Find a percentage of a number
Divide the percentage by one hundred and multiply by the base. Twenty percent of 250 is 0.20 multiplied by 250, which equals 50. Keep the base value clear because a percentage has no useful meaning without it.
Calculate a discount or markup
First calculate the percentage amount. Subtract it from the original price for a discount or add it for a markup. Fees and tax may then apply depending on the situation and should not be confused with the percentage itself.
Measure percentage change
Subtract the old value from the new value, divide the difference by the old value and multiply by one hundred. Moving from 50 to 60 is a 20 percent increase because the difference of 10 is measured against the original 50.
Use the correct base and rounding
Returning from 60 to 50 is a 16.67 percent decrease, not 20 percent, because the base is now 60. Keep extra decimal places during the calculation and round only the final result.
Quick reference table
| Item | Meaning or example |
|---|---|
| 20% of 250 | 50 |
| 15% off 200 | 170 final price |
| 50 to 60 | 20% increase |
| 60 to 50 | 16.67% decrease |
Reference and further reading
This guide is general educational information. Continue with Khan Academy — Percentages and verify important figures independently.
This article is general educational information prepared by the Calqoras Editorial Team. Verify important figures independently and consult a qualified professional where appropriate.
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