In this tutorial, we are going to learn java program to find the factorial of the number given as input from the user using for loop.

## Problem Statement

For any Input numbers given by the user, we have to calculate the factorial of that numbers.

**For example**

**Case1:** If the user input the 5.

then the output should be 120 ( 1**2**3**4**5 = 120).**Case2:** If the user input the 6.

then the output should be 720 (1**2**3**4**5*6 =720).

## What is the Factorial of a number?

The factorial of a number is the multiplication of each and every number till the given number except 0.

**For example: **

Factorial of number 4 is the multiplication of every number till number 4, i.e. 1**2**3*4 = 24

## Important Point

**• The factorial of 0 is 1• The factorial of any negative number is not defined.• The factorial only exits for whole numbers**

## Our logic to calculate Factorial of number using for loop

• Our program will create three variables i, num, factorial of long types

• Our program will take an integer input from the user which should be a whole number.

• If the number input is negative then print ‘The factorial can’t be calculated’.

• Then use for loop to calculate the factorial.

• After that, we will store the value of the factorial in a variable and finally print the value of the variable.

## Algorithm to calculate Factorial of Number

Step 1: Start

Step 2: declare variable i, num, factorial in long data-type

Step 3: initialize variable ‘factorial’ with the value 1.

Step 4: Take an integer input from user to calculate the factorial

Step 4: if(number<0):

print ‘cannot be calculated.

Else if ( number == 0):

print 1

else: for (i=1; i<=num, i++)

factorial=factorial*i

Step 5: print factorial

Step 6: Stop

## Java Program to calculate factorial using for loop

**Output** **1**

**Explanation**

The input number from the user to find the factorial is 5. The calculated value of the factorial is 120.

**Output 2**

The input number from the user to find the factorial is 8. The calculated value of the factorial is 40320.