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# 1 Factorial - 1!

Here is the answer to questions like: Calculate 1 factorial What is the factorial of 1? What is the last digits of factorial of 1? How many trailing zeros in 1 factorial? How many digits are there in 1 factorial? Use the factorial calculator below to find the factorial of any real number between 0 and 10,000.

### Factorial Calculator

 Please enter a natural number between 0 and 10000: Factorial result: ➥ The factorial of 1! is exactly 1➥ The number of trailing 0s in 1! is 0➥ The number of digits in 1 factorial is 1.➥ The factorial of 1 is 1 by definition.

## What is factorial?

### Definition of factorial

The factorial is a quantity defined any all integer x greater than or equal to 0.

The factorial is the product of all integers less than or equal to x but greater than or equal to 1. The factorial value of 0 is by definition equal to 1. For negative integers, factorials are not defined. The factorial can be seen as the result of multiplying a sequence of descending natural numbers (such as 3 Ã— 2 Ã— 1). The factorial symbol is the exclamation mark !.

### The factorial formula

If n is an natural number greater than or equal to 1, then

n! = n x (n - 1) x (n - 2) x (n - 3) ... 3 x 2 x 1

If p = 0, then p! = 1 by convention.

Example: 6! = 6 x 5 x 4 x 3 x 2 x 1 = 720

## Table of Factorials until 30

nn!
11
22
36
424
5120
6720
75040
840320
9362880
103628800
1139916800
12479001600
136227020800
1487178291200
151307674368000
1620922789888000
17355687428096000
186402373705728000
19121645100408832000
202432902008176640000
2151090942171709440000
221124000727777607680000
2325852016738884976640000
24620448401733239439360000
2515511210043330985984000000
26403291461126605635584000000
2710888869450418352160768000000
28304888344611713860501504000000
298841761993739701954543616000000
30265252859812191058636308480000000