Factorial factor is an operation symbol invented by Keyston Kramp (1760 ~1826) in 1808, and it is a mathematical term.

The factorial of a positive integer is the product of all positive integers less than or equal to this number, and the factorial of 0 is 1. The factorial writing of natural number n! . In 1808, Keyston Kaman introduced this symbol.

Which is n! =1× 2× 3× ...× n. The factor can also be defined recursively: 0! = 1，n！ =(n- 1)！ ×n .

Extended data

The factorial result of 1~ 10 is as follows:

1! = 1

2! =2* 1=2

3! =3*2* 1=6

4! =4*3*2* 1=24

5! =5*4*3*2* 1= 120

6! =6*5*4*3*2* 1=720

7! =7*6*5*4*3*2* 1=5040

8! =8*7*6*5*4*3*2* 1=40320

9! =9*8*7*6*5*4*3*2* 1=362880

10! = 10*9*8*7*6*5*4*3*2* 1=3628800

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