# Java Program to Find Factorial of a Number

Factorial of a number is the multiplication of a number with all the integers less than it. Factorial of a number is written as the number followed by exclamation symbol **!**. For Example, Factorial of 4 is written as 4!.

n! = n * (n - 1)! 0! = 1 1! = 1 4! = 4 * 3 * 2 * 1 = 24 5! = 5 * 4 * 3 * 2 * 1 = 120 6! = 6 * 5 * 4 * 3 * 2 * 1 = 720

## Algorithm

- Set factorial as
**1** - Store the Number for which you want to find the factorial in a variable say
**i** - Multiply
**factorial * i**and store in**factorial** - Decrement
**i**and store in**i**itself - Repeat the above steps until i=1

## Factorial of a Number - Java Program

```
public class FactorialOfANumber {
public static void main (String args[]) {
int num = 5;
System.out.print("Factorial of the Number " + num + " = ");
int factorial=1;
for(int i = num; i >= 1 ; i--) {
System.out.print(""+ i );
factorial = factorial * i;
if(i!=1) System.out.print(" * ");
}
System.out.print("=" + factorial);
}
}
```

Output of the Java program would be:

Factorial of the Number 5 = 5 * 4 * 3 * 2 * 1=120

## Factorial of Some Numbers

Number | Calculation | Value |
---|---|---|

0 factorial | 1 | 1 |

1 factorial | 1 | 1 |

2 factorial | 2 * 1 | 2 |

3 factorial | 3 * 2 * 1 | 6 |

4 factorial | 4 * 3! | 24 |

5 factorial | 5 * 4! | 120 |

6 factorial | 6 * 5! | 720 |

7 factorial | 7 * 6! | 5,040 |

8 factorial | 8 * 7! | 40,320 |

9 factorial | 9 * 8! | 362,880 |

10 factorial | 10 * 9! | 3,628,800 |

11 factorial | 11 * 10! | 3,991,680 |

100 factorial | 100 * 99! | 9.332622e+157 |