### Armstrong Number

If the given number is equal to the sum of the Nth power of each digit present in that integer then, that number can be Armstrong Number. For example 370 is Armstrong Number.

Number of individual digits in 370 = 3

370 = 3³ + 7³ + 0³

= 27 + 343 + 0 = 370

Below steps will show you the common approach to check for the Armstrong Number

**Steps:**

- User has to enter any number
- Counting the Number of individual digits (For Example, 370 means 3)
- Divide the given number into individual digits (For Example, Divide 370 into 3, 7 and 0)
- Calculate the power of n for each individual and add those numbers
- Compare original value with Sum value.
- If they exactly matched then it is Armstrong number else it is not Armstrong

In this article we will show you, How to Write Python Program For Armstrong Number Using While Loop, For Loop, Functions and Recursion. We will also show you, Armstrong Numbers between 1 to n.

## Python Program for Armstrong Number Using While Loop

This Python program allows the user to enter any positive integer and then, this program will check whether a number is Armstrong Number or Not using the Python While Loop

**PYTHON CODE**

# Python Program For Armstrong Number using While Loop Number = int(input("\nPlease Enter the Number to Check for Armstrong: ")) # Initializing Sum and Number of Digits Sum = 0 Times = 0 # Calculating Number of individual digits Temp = Number while Temp > 0: Times = Times + 1 Temp = Temp // 10 # Finding Armstrong Number Temp = Number while Temp > 0: Reminder = Temp % 10 Sum = Sum + (Reminder ** Times) Temp //= 10 if Number == Sum: print("\n %d is Armstrong Number.\n" %Number) else: print("\n %d is Not a Armstrong Number.\n" %Number)

**OUTPUT**

**ANALYSIS**

This program allows the user to enter any positive integer and then, that number is assigned to variable Number.

Next, We assign the original value to the Temp variable. This will help us to preserve our original value and then do all the manipulation on Temp variable.

Below While loop will make sure that, the given number is greater than 0. Statements inside the while loop will split the numbers and counts number of individual digits inside the given number. If you don’t understand the logic, Please refer Python Program to find Number Of Digits in a Number article.

while Temp > 0: Times = Times + 1 Temp = Temp // 10

while Temp > 0: Reminder = Temp % 10 Sum = Sum + (Reminder ** Times) Temp //= 10

User Entered value: Number = 9474 and Sum = 0

Temp = Number

Temp = 9474

**First Iteration**

Reminder = Temp %10

Reminder = 9474 % 10 = 4

Sum = Sum + pow (Reminder, Times)

For this example, Times =4 because number of digits in 9474 = 4. So,

Sum = Sum + (Reminder * Reminder * Reminder * Reminder)

Sum = 0 + (4 * 4 * 4 * 4)

Sum = 0 + 256

Sum = 256

Temp = Temp /10

Temp = 9474 /10

Temp = 947

**NOTE:** If the number of digits count is 5 then Reminder will be multiplied by 5 times.

**Second Iteration**

From the first Iteration the values of both Temp and Sum has been changed as: Temp = 163 and Sum = 256

Reminder = Temp %10

Reminder = 947 % 10 = 7

Sum = Sum + (Reminder * Reminder * Reminder * Reminder)

Sum = 256 + (7 * 7 * 7 * 7)

Sum = 256 + 2401

Sum = 2657

Temp = Temp /10

Temp = 163 /10

Temp = 94

**Third Iteration**

From the Third Iteration the values of both Temp and Sum has been changed as:

Temp = 94 and Sum = 2657

Reminder = Temp %10

Reminder = 94 % 10 = 4

Sum = Sum + (Reminder * Reminder * Reminder * Reminder)

Sum = 2657 + (4 * 4 * 4 * 4)

Sum = 2657 + 256

Sum = 2913

Temp = Temp /10

Temp = 94 /10

Temp = 9

**Fourth Iteration**

From the Fourth Iteration the values of both Temp and Sum has been changed as:

Temp = 9 and Sum = 2913

Reminder = Temp %10

Reminder = 9 % 10 = 0

Sum = Sum + (Reminder * Reminder * Reminder * Reminder)

Sum = 2913 + (9 * 9 * 9 * 9)

Sum = 2913 + 6561

Sum = 9474

Temp = Temp /10

Temp = 9/10

Temp = 0

**Here **Number = 0 so, the while loop condition will fail

if ( Number == Sum ) – Condition will check whether the user enter number is exactly equal to Sum number or not. If this condition is True, then it is Armstrong else the given number is not Armstrong number

if ( Number == Sum )

if(9474 == 9474) –TRUE, Means Armstrong

**NOTE: **If you are finding the Armstrong number below 1000 then you can simply remove the while loop to count the number of digits in a number and then replace the below code

Sum = Sum + (Reminder ** Times); With Sum = Sum + (Reminder * Reminder * Reminder)

## Python Program for Armstrong Number Using For Loop

This Python program allows the user to enter any positive integer and then, this program will check whether a number is Armstrong Number or Not using Python For Loop

**PYTHON CODE**

# Python Program For Armstrong Number using For Loop Number = int(input("\nPlease Enter the Number to Check for Armstrong: ")) # Initializing Sum and Number of Digits Sum = 0 Times = 0 # Calculating Number of individual digits Temp = Number while Temp > 0: Times = Times + 1 Temp = Temp // 10 # Finding Armstrong Number Temp = Number for n in range(1, Temp + 1): Reminder = Temp % 10 Sum = Sum + (Reminder ** Times) Temp //= 10 if Number == Sum: print("\n %d is Armstrong Number.\n" %Number) else: print("\n %d is Not a Armstrong Number.\n" %Number)

**OUTPUT**

We just replaced the While loop in the above example with the For loop. If you don’t understand the for loop then please refer For Loop article here: Python For Loop

## Python Program for Armstrong Number Using Functions

This Python program allows the user to enter any positive integer and then, this program will check whether a number is Armstrong Number or Not using Functions

**PYTHON CODE**

# Python Program For Armstrong Number using Functions def Armstrong_Number(Number): # Initializing Sum and Number of Digits Sum = 0 Times = 0 # Calculating Number of individual digits Temp = Number while Temp > 0: Times = Times + 1 Temp = Temp // 10 # Finding Armstrong Number Temp = Number for n in range(1, Temp + 1): Reminder = Temp % 10 Sum = Sum + (Reminder ** Times) Temp //= 10 return Sum #End of Function #User Input Number = int(input("\nPlease Enter the Number to Check for Armstrong: ")) if (Number == Armstrong_Number(Number)): print("\n %d is Armstrong Number.\n" %Number) else: print("\n %d is Not a Armstrong Number.\n" %Number)

**OUTPUT**

**ANALYSIS**

In this example we defined following function to perform all the necessary calculations and return Sum

def Armstrong_Number(Number):

When the compiler reaches to following code inside If statement then, the compiler will immediately jump to above specified function

Armstrong_Number(Number)

We already explained LOGIC above example.

## Python Program for Armstrong Number Using Recursion

This Python program allows the user to enter any positive integer and then, this program will check whether a number is Armstrong Number or Not using Recursion concept.

**PYTHON CODE**

# Python Program For Armstrong Number using Recursion # Initializing Number of Digits Sum = 0 Times = 0 # Calculating Number of individual digits def Count_Of_Digits(Number): global Times if(Number > 0): Times = Times + 1 Count_Of_Digits(Number // 10) return Times #End of Count Of Digits Function # Finding Armstrong Number def Armstrong_Number(Number, Times): global Sum if(Number > 0): Reminder = Number % 10 Sum = Sum + (Reminder ** Times) Armstrong_Number(Number //10, Times) return Sum #End of Armstrong Function #User Input Number = int(input("\nPlease Enter the Number to Check for Armstrong: ")) Times = Count_Of_Digits(Number) Sum = Armstrong_Number(Number, Times) if (Number == Sum): print("\n %d is Armstrong Number.\n" %Number) else: print("\n %d is Not a Armstrong Number.\n" %Number)

**OUTPUT**

**ANALYSIS**

In this example we defined two recursive functions. Following function will accept integer values as parameter value and count the number of individual digits in a number recursively.

def Count_Of_Digits(Number):

Following function will accept two integer values as parameter values and will perform all the necessary calculations and return Sum

def Armstrong_Number(Number, Times):

Following Statement will help to call the function Recursively with updated value. If you miss this statement then, after completing the first line it will terminate. For example,

Armstrong_Number(Number //10, Times)

Number = 153

Then the output will be 27

Lets see the If statement inside the above specified functions

if (Number > 0) will check whether the number is greater than 0 or not. For Recursive functions it is very important to place a condition before using the function recursively otherwise, we will end up in infinite execution (Same like infinite Loop).

Please be careful :)

## Python Program to Find Armstrong Numbers between the 1 to n

This Python program allows the user to enter minimum and maximum values. This program will find the Armstrong Numbers between the Minimum and Maximum values.

**PYTHON CODE**

# Python Program to Find Armstrong Numbers between the 1 to n Minimum = int(input("Please Enter the Minimum Value: ")) Maximum = int(input("\n Please Enter the Maximum Value: ")) for Number in range(Minimum, Maximum + 1): # Initializing Sum and Number of Digits Sum = 0 Times = 0 # Calculating Number of individual digits Temp = Number while Temp > 0: Times = Times + 1 Temp = Temp // 10 # Finding Armstrong Number Temp = Number while Temp > 0: Reminder = Temp % 10 Sum = Sum + (Reminder ** Times) Temp //= 10 if Number == Sum: print(Number)

**OUTPUT**

**ANALYSIS:**

Following statements present in this program allows the user to enter minimum and maximum values.

Minimum = int(input("Please Enter the Minimum Value: ")) Maximum = int(input("\n Please Enter the Maximum Value: "))

This For Loop helps compiler to iterate between Minimum and Maximum Variables, iteration starts at the Minimum and then it will not exceed Maximum variable.

for Number in range(Minimum, Maximum + 1):

if(Number == Sum) -– condition will check whether the sum of the power N for each digit present in that integer is equal to given number or not. If this condition is True, then it is Armstrong else the given number is not Armstrong number.

If this condition is True then, below statement will be printed

print(Number)

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