How to find 40 percent of 30
"Percent" means per hundred, so 40% is the fraction 40/100, or 0.4 as a decimal. Taking 40 percent of 30 means multiplying 30 by that fraction:
40% of 30 = 30 x 40 / 100
= 1,200 / 100
= 12The same answer comes from the decimal form: 30 x 0.4 = 12. And because multiplication is commutative, 40% of 30 equals 30% of 40, which is sometimes the easier way to see it in your head.
Mental math shortcut
10% of 30 is 3 (move the decimal one place left), and 1% is 0.3. Build 40% from those pieces: 4 x 3 = 12.
Nearby percentages of 30
| Percent | Of 30 | 30 minus it | 30 plus it |
|---|---|---|---|
| 1% | 0.3 | 29.7 | 30.3 |
| 5% | 1.5 | 28.5 | 31.5 |
| 10% | 3 | 27 | 33 |
| 15% | 4.5 | 25.5 | 34.5 |
| 20% | 6 | 24 | 36 |
| 25% | 7.5 | 22.5 | 37.5 |
| 30% | 9 | 21 | 39 |
| 35% | 10.5 | 19.5 | 40.5 |
| 39% | 11.7 | 18.3 | 41.7 |
| 41% | 12.3 | 17.7 | 42.3 |
| 45% | 13.5 | 16.5 | 43.5 |
| 50% | 15 | 15 | 45 |
40 percent of other amounts
| Amount | 40% of it |
|---|---|
| 10 | 4 |
| 20 | 8 |
| 25 | 10 |
| 40 | 16 |
| 50 | 20 |
| 60 | 24 |
| 75 | 30 |
| 80 | 32 |
| 100 | 40 |
| 120 | 48 |
Where this comes up
A 40% discount on a 30 price takes off 12, leaving 18. A 40% tip or tax on 30 adds 12, for a total of 42. If 30 is a score out of a possible total, 40% of it is the share 12 represents. For percent change, reverse percentages, and "X is what percent of Y", use the full percentage calculator.