# What is 66 factorial ?

Steps to calculate factorial of 66

## How to calculate the factorial of 66

To find 66 factorial, or 66!, simply use the formula that multiplies the number 66 by all positive whole numbers less than it.

Let's look at how to calculate the Factorial of Sixty-six :

66! is exactly : 544344939077443064003729240247842752644293064388798874532860126869671081148416000000000000000

Factorial of 66 can be calculated as:
66! = 66 x 65 x 64 x 63 x ... x 3 x 2 x 1

The number of trailing zeros in 66! is 15

The number of digits in 66 factorial is 93.

## What Is Factorial?

A factorial is represented by an integer and an exclamation symbol. In math concepts, factorial is a multiplication treatment of natural numbers .

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

Symbolically, it is displayed as "!".

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

## Factorial Formula

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

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

The expansion of the formula shows the numbers to be multiplied with each other to obtain the factorial of the number.

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

So the rule is : n! = n × (n−1)!

Example :
66! Factorial = 66 x 65 x 64 x 63 x ... x 3 x 2 x 1 = 66 × 65! = 544344939077443064003729240247842752644293064388798874532860126869671081148416000000000000000

## 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.