In this article, we will learn how to find the factorial of a number in java. The factorial of a number is the product of all integers from 1 to that number. Before moving forward make sure you are familiar with loops in java.

```
Example:
Enter the number: 5
Output:
A factorial of 5 is 120
```

## Method 1: Find the factorial of a number in java.

In this method, we will learn how to find the factorial of a number in java using a while loop.

### Algorithm to find the factorial of a given number using a while loop

- Create an instance of a Scanner class.
- Declare and initialize the new variable.
- Declare a new variable for the loop and store the factorial of a number.
- Initialize both variables with 1.
- Traverse using a while loop.
- Run the loop till the given number.
- Update the factorial in each iteration of the number.
- Increment the loop variable.
- Print the factorial of a number.

### Code Implementation of java program to find factorial of a number using while loop:

import java.util.*; public class Main { public static void main(String []args) { Scanner sc=new Scanner(System.in); System.out.println("Enter the number: "); int num=sc.nextInt(); int i=1,fact=1; while(i<=num) { fact=fact*i; i++; } System.out.println("Factorial of the number: "+fact); } }

```
Output:
Enter the number: 5
Factorial of the number: 120
```

## Method 2: Java program to find the factorial of a number

In this method, we will use a for loop to find the factorial number.

### Algorithms to find the factorial of a given number using for loop.

- Create an instance of a Scanner class.
- Declare and initialize the new variable.
- Declare a new variable for the loop and store the factorial of a number.
- Initialize both variables with 1.
- Use a for loop to calculate the factorial.
- Update the factorial variable by multiplying it with the loop variable in each iteration.
- Print the factorial of the given number.

### Code Implementation java program to find factorial of a number using For loop:

import java.util.*; public class Main { public static void main(String []args) { Scanner sc=new Scanner(System.in); System.out.println("Enter the number: "); int num=sc.nextInt(); int fact=1; for(int i=1;i<=num;i++) { fact=fact*i; } System.out.println("Factorial of the number: "+fact); } }

## Method 3: Java program to find the factorial of a given number recursively.

In this method, we will find the factorial of a given number recursively, In this program, we will take input from the user and we calculate the factorial of a number recursively.

### Algorithm to find the factorial of a given number recursively

- Declare a variable to store a number.
- Ask the user to enter the input number.
- Check whether it is possible to calculate the factorial or not.
- If the number is greater than and equal to 0, then call a recursive function to calculate the factorial of the entered number.
- If the number is lesser than 0, print the message that it is not possible to calculate the factorial.
- If the entered number is 0 or 1, then return 1.
- If the entered number is other than 0 or 1, then calculate the factorial by recursively calling the same method.
- Return the result and print the factorial of a given number

### Code Implementation of java program to find factorial of a number:

import java.util.Scanner; public class Main { public static void main(String[] args) { Scanner sc = new Scanner(System.in); System.out.println("Enter the number :"); int num = sc.nextInt(); if(num>=0) { int factorial=findFactorial(num); System.out.println("The factorial of the entered number is :"+factorial); } else { System.out.println("Factorial not possible."); System.out.println("Please enter valid input."); } } public static int findFactorial(int num) { if(num==0) return 1; else if(num==1) return 1; else return num*findFactorial(num-1); } }

```
Output:
Enter the number: 6
The factorial of the entered number is:720
```

**Conclusion**

In the above article, we have discussed different approaches to finding the factorial of a given number in Java. We hope this article helps you to enhance your knowledge and gives you a grasp to solve more similar problems. Also, you can visit PrepBytes for practicing more similar questions. Many serviced based companies like Wipro, TCS, Capgemini, Infosys, and Accenture have asked logic-building questions likes finding the factorial of a number in their process of hiring.

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