# Python Program to Check if a Number is Peterson Number

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Given a number, the task is to check whether the given number is a Peterson number or not.

Peterson Number:

The Peterson number is the number whose sum of factorials of each digit equals the number itself. Let me give you an example to help you understand:

Examples:

Example1:

Input:

Given number =1

Output:

The given number [ 1 ] is a Peterson number

Example2:

Input:

Given number =145

Output:

The given number [ 145 ] is a Peterson number

## Program to Check if a Number is Peterson Number in Python

Below are the ways to check whether the given number is a Peterson number or not.

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

Approach:

• Import the math module using the import keyword.
• Give the number as static input and store it in a variable.
• Take a variable psum and initialize its value to 0.
• Convert the given number to a string using the str() function.
• Convert the given number into a list of digits using list(),map(),int,split() functions.
• Traverse in this list of digits using For loop.
• Calculate the factorial of the list value using math.factorial() function.
• Add this factorial value to psum.
• Check if psum is equal to the given number using the If statement.
• If it is true then it is a Peterson number.
• Else it is not Peterson’s number.
• The Exit of the Program.

Below is the implementation:

# Import the math module using the import keyword.
import math
# Give the number as static input and store it in a variable.4
gvnnumb = 145
# Take a variable psum and initialize its value to 0.
psum = 0
# Convert the given number to a string using the str() function.
strnumbe = str(gvnnumb)
# Convert the given number into a list of
# digits using list(),map(),int,split() functions.
lstdigts = list(map(int, strnumbe))
# Traverse in this list of digits using For loop.
for dgtnumbr in lstdigts:
# Calculate the factorial of the list value using math.factorial() function.
numbfact = math.factorial(dgtnumbr)
# Add this factorial value to psum.
psum = psum+numbfact
# Check if psum is equal to the given number using the If statement.
if(psum == gvnnumb):
# If it is true then it is a Peterson number.
print('The given number [', gvnnumb, '] is a Peterson number')
# Else it is not Peterson's number.
else:
print('The given number [', gvnnumb, '] is not a Peterson number')


Output:

The given number [ 145 ] is a Peterson number

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

Approach:

• Import the math module using the import keyword.
• Give the number as user input using int(input()) and store it in a variable.
• Take a variable psum and initialize its value to 0.
• Convert the given number to a string using the str() function.
• Convert the given number into a list of digits using list(),map(),int,split() functions.
• Traverse in this list of digits using For loop.
• Calculate the factorial of the list value using math.factorial() function.
• Add this factorial value to psum.
• Check if psum is equal to the given number using the If statement.
• If it is true then it is a Peterson number.
• Else it is not Peterson’s number.
• The Exit of the Program.

Below is the implementation:

# Import the math module using the import keyword.
import math
# Give the number as user input using int(input()) and store it in a variable.
gvnnumb = int(input(
'Enter some random number to check whether the given number is a Peterson or not = '))
# Take a variable psum and initialize its value to 0.
psum = 0
# Convert the given number to a string using the str() function.
strnumbe = str(gvnnumb)
# Convert the given number into a list of
# digits using list(),map(),int,split() functions.
lstdigts = list(map(int, strnumbe))
# Traverse in this list of digits using For loop.
for dgtnumbr in lstdigts:
# Calculate the factorial of the list value using math.factorial() function.
numbfact = math.factorial(dgtnumbr)
# Add this factorial value to psum.
psum = psum+numbfact
# Check if psum is equal to the given number using the If statement.
if(psum == gvnnumb):
# If it is true then it is a Peterson number.
print('The given number [', gvnnumb, '] is a Peterson number')
# Else it is not Peterson's number.
else:
print('The given number [', gvnnumb, '] is not a Peterson number')


Output:

Enter some random number to check whether the given number is a Peterson or not = 1
The given number [ 1 ] is a Peterson number

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