# What is 45 factorial ?

Steps to calculate factorial of 45

## How to calculate the factorial of 45

To find 45 factorial, or 45!, simply use the formula that multiplies the number 45 by all positive whole numbers less than it.

Let's look at how to calculate the Factorial of Forty-five :

45! is exactly : 119622220865480194561963161495657715064383733760000000000

Factorial of 45 can be calculated as:
45! = 45 x 44 x 43 x 42 x ... x 3 x 2 x 1

The number of trailing zeros in 45! is 10

The number of digits in 45 factorial is 57.

## What Is Factorial?

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

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

Symbolically, it is displayed as "!".

The function is used, among other things, to find the "n" way objects can be positioned .

## Factorial Formula

To find the factorial of any given number, substitute the exact value for n in the given way :

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

The expansion of the formula shows the numbers to be replicated together with each other to receive the factorial of the number.

We can also calculate a factorial from the prior one. The factorial of any number is that number replicated the factorial of (that number minus 1).

So the rule is : n! = n × (n−1)!

Example :
45! Factorial = 45 x 44 x 43 x 42 x ... x 3 x 2 x 1 = 45 × 44! = 119622220865480194561963161495657715064383733760000000000

## 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 own value is corresponding to 1. So, 0! = 1.