1! (the factorial of 1) is 1.
1! (the factorial of 1) is 1.
The factorial of a whole number n is the product of every whole number from n down to 1. By definition, 1! = 1 (and 0! is also 1).
1! = 1 = 1
1! has 1 digit. Factorials grow very quickly: each step multiplies by a bigger number than the last.
Many calculators show the result in scientific notation for large factorials.
| 1! | = 1 |
| 0! | = 1 |
| 1! ÷ 1! | = 1 |
| n | n! | Digits |
|---|---|---|
| 1! | 1 | 1 digits |
| 2! | 2 | 1 digits |
| 3! | 6 | 1 digits |
| 4! | 24 | 2 digits |
| 5! | 120 | 3 digits |
| 6! | 720 | 3 digits |
| 7! | 5,040 | 4 digits |
| 8! | 40,320 | 5 digits |
| 9! | 362,880 | 6 digits |
| 10! | 3,628,800 | 7 digits |
| 11! | 39,916,800 | 8 digits |
| 12! | 479,001,600 | 9 digits |
| 13! | 6,227,020,800 | 10 digits |
| 14! | 87,178,291,200 | 11 digits |
| 15! | 1,307,674,368,000 | 13 digits |
| 16! | 20,922,789,888,000 | 14 digits |
| 17! | 355,687,428,096,000 | 15 digits |
| 18! | 6,402,373,705,728,000 | 16 digits |
| 19! | 121,645,100,408,832,000 | 18 digits |
| 20! | 2,432,902,008,176,640,000 | 19 digits |
1! (the factorial of 1) is 1.
Multiply all whole numbers from 1 down to 1: 1 = 1.
1! has 1 digit.
0! is defined as 1, which keeps formulas for permutations and combinations consistent.
Yes. Use the calculator on this page, or open the full free Scientific Calculator with memory, history and keyboard support.