How to find 90 percent of 20
"Percent" means per hundred, so 90% is the fraction 90/100, or 0.9 as a decimal. Taking 90 percent of 20 means multiplying 20 by that fraction:
90% of 20 = 20 x 90 / 100
= 1,800 / 100
= 18The same answer comes from the decimal form: 20 x 0.9 = 18. And because multiplication is commutative, 90% of 20 equals 20% of 90, which is sometimes the easier way to see it in your head.
Mental math shortcut
10% of 20 is 2 (move the decimal one place left), and 1% is 0.2. Build 90% from those pieces: 9 x 2 = 18.
Nearby percentages of 20
| Percent | Of 20 | 20 minus it | 20 plus it |
|---|---|---|---|
| 1% | 0.2 | 19.8 | 20.2 |
| 5% | 1 | 19 | 21 |
| 10% | 2 | 18 | 22 |
| 15% | 3 | 17 | 23 |
| 20% | 4 | 16 | 24 |
| 25% | 5 | 15 | 25 |
| 30% | 6 | 14 | 26 |
| 50% | 10 | 10 | 30 |
| 75% | 15 | 5 | 35 |
| 85% | 17 | 3 | 37 |
| 89% | 17.8 | 2.2 | 37.8 |
| 91% | 18.2 | 1.8 | 38.2 |
90 percent of other amounts
| Amount | 90% of it |
|---|---|
| 10 | 9 |
| 25 | 22.5 |
| 30 | 27 |
| 40 | 36 |
| 50 | 45 |
| 60 | 54 |
| 75 | 67.5 |
| 80 | 72 |
| 100 | 90 |
Where this comes up
A 90% discount on a 20 price takes off 18, leaving 2. A 90% tip or tax on 20 adds 18, for a total of 38. If 20 is a score out of a possible total, 90% of it is the share 18 represents. For percent change, reverse percentages, and "X is what percent of Y", use the full percentage calculator.