# What is 15 factorial ?

Steps to calculate factorial of 15

## How to calculate the factorial of 15

To find 15 factorial, or 15!, simply use the formula that multiplies the number 15 by all positive whole numbers less than it.

Let's look at how to calculate the Factorial of Fifteen :

15! is exactly : 1307674368000

Factorial of 15 can be calculated as:
15! = 15 x 14 x 13 x 12 x ... x 3 x 2 x 1

The number of trailing zeros in 15! is 3

The number of digits in 15 factorial is 13.

## What Is Factorial?

A factorial is represented by an integer and an exclamation tag. In Mathematics, factorial is a multiplication process of natural numbers .

It multiplies the number by every noreal number that is less than it .

Symbolically, it is represented as "!".

The function is used, among other things, to get the "n" way elements can be established .

## Factorial Formula

To find the factorial of any given number, replace the exact value for n in the given method :

n! = n × (n-1) × (n-2) × (n-3) × ….× 3 × 2 × 1

The expansion of the formula provides the numbers to be replicated at the same time to receive the factorial of the number.

We can also determine a factorial from the previous one. The factorial of any number is that number times the factorial of (that number minus 1).

So the rule is : n! = n × (n−1)!

Example :
15! Factorial = 15 x 14 x 13 x 12 x ... x 3 x 2 x 1 = 15 × 14! = 1307674368000

## What are Factorials Used For?

The best use of factorial is in Combinations and Permutations.

Example : Determine how to arrange letters without repeating?

There one way for 1 letter "a":
2 ways for two letters "ab": ab, ba.
There are 6 ways for 3 letters "abc": abc acb cab bac bca.
There are 24 ways for 1234 of the letters "abcd"

## Frequently Asked Questions on Factorial

### Can we have factorials for negative numbers ?

Negative integer factorials are undefined

### What Is 0!

Zero factorial or Factorial of 0 is simple, and its value is equal to 1. So, 0! = 1.