We are back to this Java questions and programming question series. In this blog post, we are going to cover a very important programming question: How will you find the factorial number? In mathematics, we have seen factorial numbers. So now we will find out:

- How will you find out the factorial number?
- What are the different ways to find out the factorial number?
- What are the different conditions you will handle?

Post Type: | Java Programs For Beginners |

Published On: | www.softwaretestingo.com |

Applicable For: | Freshers & Experience |

Get Updates: | Join Our Telegram Group |

It’s an evergreen interview question whether you are going for a Java or an automation interview.

So, what do you mean by factorial number? The Factorial of a positive integer (number) is the sum of the multiplication of all the integers smaller than that positive integer.

A factorial number of 3 means I just need to write like this: 3 x 2 x 1 is equal to 6. Right? If I ask you what a factorial of 4 is, factorial 4 is like this: 4 x 3 x 2 x 1.

Note: The factorial of 1 is 1, and the Factorial of 0 (zero) is 1.

### Factorials of Numbers 1 to 10 Table

Here is the List Of factorial numbers from 1 to 10.

Factorial of a Number! | Expansion | Value |

1! | 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 | 5,040 |

8! | 8 × 7 × 6 × 5 × 4 × 3 × 2 × 1 | 40,320 |

9! | 9 × 8 × 7 × 6 × 5 × 4 × 3 × 2 × 1 | 362,880 |

10! | 10 × 9 ×8 × 7 × 6 × 5 ×4 × 3 × 2 × 1 | 3,628,800 |

## What are the different ways to find out the factorial number?

There are two ways to find the factorial of a number. We can find factorial with the help of recursive and non-recursive methods.

### Factorial Number Without Using Recursive Method

package com.softwaretestingo.interviewprograms; import java.util.Scanner; public class FactorialNumberEx1 { // Find Factorial Using Recursive Method public static int factoral(int num) { int fact=1; if(num==0) return 1; for(int i=1;i<=num;i++) { fact=fact*i; } return fact; } public static void main(String[] args) { // fact (3)=3x2x1 Scanner sc=new Scanner(System.in); System.out.println("Enter A Number To Find out Factorial: "); int number=sc.nextInt(); System.out.println("The Factorial of "+number+ " is = "+factoral(number)); } }

Output:

Enter A Number To Find out Factorial: 5 The Factorial of 5 is = 120

### Factorial Number Using Recursive Method

If you’re working with Java, you may come across situations where a method needs to call itself. In these cases, the method is known as a recursive method, and the process is called recursion.

package com.softwaretestingo.interviewprograms; import java.util.Scanner; public class FactorialNumberEx2 { // Find Factorial Using Recursive Method public static int factoral(int num) { if (num==0) return 1; else return (num * factoral(num-1)); } public static void main(String[] args) { // fact (3)=3x2x1 Scanner sc=new Scanner(System.in); System.out.println("Enter A Number To Find out Factorial: "); int number=sc.nextInt(); System.out.println("The Factorial of "+number+ " is = "+factoral(number)); } }

Output:

Enter A Number To Find out Factorial: 8 The Factorial of 8 is = 40320