In the previous article, we have discussed Python Program to Calculate the Surface Area and Volume of a Hemisphere

**Factorial:**

The product of all positive integers less than or equal to n is the factorial of a non-negative integer n, denoted by n! in mathematics:

**n! = n * (n – 1) *(n – 2) * . . . . . . . . . . 3 * 2 * 1.**

4 != 4 * 3 * 2 *1= 24

Given a number **N** and the task is to calculate the value of 1/N!

**Examples:**

**Example1:**

**Input:**

Given Number = 4

**Output:**

The value of 1/n! with given n value{ 4 } = 0.041666666666666664

**Example2:**

**Input:**

Given Number = 6

**Output:**

The value of 1/n! with given n value{ 6 } = 0.001388888888888889

## Program to Compute 1/N! in Python

Below are the ways to calculate the value of 1/N! :

### Method #1: Using For Loop (Static Input)

**Approach:**

- Give the number as static input and store it in a variable.
- Take a variable, initialize it with the value ‘1’, and store it in another variable say ‘
**factorl**‘. - Loop from 1 to the given number using the for loop.
- Inside the loop, calculate the factorial of a given number by multiplying the value of the above variable “
**factorl**” with the iterator value. - Store it in the same variable ‘
**factorl**‘. - Calculate the value of 1/
**factorl**and store it in another variable. - Print the value of 1/N! for the given number.
- The Exit of the Program.

**Below is the implementation:**

# Give the number as static input and store it in a variable. gven_nval = 4 # Take a variable, initialize it with the value '1', and store it in another variable say # 'factorl'. factorl = 1 # Loop from 1 to the given number using the for loop. for itr in range(1, gven_nval+1): # Inside the loop, calculate the factorial of a given number by multiplying the value of # the above variable "factorl" with the iterator value. # Store it in the same variable 'factorl'. factorl *= itr # Calculate the value of 1/factorl and store it in another variable. fnl_reslt = 1.0/factorl # Print the value of 1/N! for the given number. print("The value of 1/n! with given n value{", gven_nval, "} =", fnl_reslt)

**Output:**

The value of 1/n! with given n value{ 4 } = 0.041666666666666664

### Method #2: Using For loop (User Input)

**Approach:**

- Give the number as user input using the int(input()) function and store it in a variable.
- Take a variable, initialize it with the value ‘1’, and store it in another variable say ‘
**factorl**‘. - Loop from 1 to the given number using the for loop.
- Inside the loop, calculate the factorial of a given number by multiplying the value of the above variable “
**factorl**” with the iterator value. - Store it in the same variable ‘
**factorl**‘. - Calculate the value of 1/
**factorl**and store it in another variable. - Print the value of 1/N! for the given number.
- The Exit of the Program.

**Below is the implementation:**

# Give the number as user input using the int(input()) function and store it in a variable. gven_nval = int(input("Enter some random Number = ")) # Take a variable, initialize it with the value '1', and store it in another variable say # 'factorl'. factorl = 1 # Loop from 1 to the given number using the for loop. for itr in range(1, gven_nval+1): # Inside the loop, calculate the factorial of a given number by multiplying the value of # the above variable "factorl" with the iterator value. # Store it in the same variable 'factorl'. factorl *= itr # Calculate the value of 1/factorl and store it in another variable. fnl_reslt = 1.0/factorl # Print the value of 1/N! for the given number. print("The value of 1/n! with given n value{", gven_nval, "} =", fnl_reslt)

**Output:**

Enter some random Number = 6 The value of 1/n! with given n value{ 6 } = 0.001388888888888889

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