Percentage calculator
15% of 80 is 12. Adding it gives 92; taking it off gives 68.
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The numbers for these inputs
| Percent | Of the number | Number plus it | Number minus it |
|---|---|---|---|
| 5% | 4 | 84 | 76 |
| 10% | 8 | 88 | 72 |
| 15% | 12 | 92 | 68 |
| 20% | 16 | 96 | 64 |
| 25% | 20 | 100 | 60 |
| 30% | 24 | 104 | 56 |
| 40% | 32 | 112 | 48 |
| 50% | 40 | 120 | 40 |
How it works
A percent is a part of 100, so X percent of a number is the number x X / 100. For 15 percent of 80: 80 x 15 / 100 = 12.
To add a percent (a price rise, a tip, a tax), multiply by 1 + X/100. To take it off (a discount), multiply by 1 - X/100.
The table shows the same number at common percentages so you can compare at a glance.
Common mistakes
- Adding a percent and then taking the same percent off: +20% then -20% does not return to the start, it leaves you 4% lower.
- Mixing up percent and percentage points: going from 10% to 12% is 2 points, but a 20% increase.
- Taking a percent of the wrong base, for example a discount of the final price instead of the original.
Questions
What is 15 percent of 80?
12. It is 80 x 15 / 100.
What is 80 plus 15 percent?
92.
What is 80 minus 15 percent?
68, for example a 15% discount on a price of 80.
12 is what percent of 80?
15%. Divide the part by the whole and multiply by 100.