What is 91 factorial ?

Steps to calculate factorial of 91

How to calculate the factorial of 91

To find 91 factorial, or 91!, simply use the formula that multiplies the number 91 by all positive whole numbers less than it.

Let's look at how to calculate the Factorial of Ninety-one :

  91! is exactly : 135200152767840296255166568759495142147586866476906677791741734597153670771559994765685283954750449427751168336768008192000000000000000000000

  Factorial of 91 can be calculated as:
91! = 91 x 90 x 89 x 88 x ... x 3 x 2 x 1

  The number of trailing zeros in 91! is 21

  The number of digits in 91 factorial is 141.

What Is Factorial?

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

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

Symbolically, it is displayed as "!".

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

Factorial Formula

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

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

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

We can also determine 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 :
91! Factorial = 91 x 90 x 89 x 88 x ... x 3 x 2 x 1 = 91 × 90! = 135200152767840296255166568759495142147586866476906677791741734597153670771559994765685283954750449427751168336768008192000000000000000000000

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

1) Can we have factorials for negative numbers ?
  Negative integer factorials are undefined

2) What Is 0!
 Zero factorial or Factorial of 0 is simple, and its own value is equal to 1. So, 0! = 1.

Other conversions of the number 91