JavaScript Program to Find the Factorial of a Number

The factorial of a number is the product of all the numbers from 1 to that number. For example,

factorial of 5 is equal to 1 * 2 * 3 * 4 * 5 = 120.

The factorial of a positive number n is given by:

factorial of n (n!) = 1 * 2 * 3 * 4.....n

The factorial of negative numbers do not exist and the factorial of 0 is 1.

Example: Find Factorial

Output

Enter a positive integer: 5
The factorial of 5 is 120.

In the above program, the user is prompted to enter an integer. Then if...else if...else statement is used to check the condition of a number.

• When the user enters a negative number, an error message is shown.
• When the user enters 0, the factorial is 1.
• When the user enters a positive integer, a for loop is used to iterate over 1 to the number entered by the user to find the factorial.
• Each number is multiplied and stored in the fact variable.