In this post, We will be going to see different ways to write a code in Python for checking a number is Armstrong or not?

Armstrong number is a number in which the sum of each digit raised to the power of a number of digits present in a given number is equal to the number itself.

Example:

Input: Number = 153
Output: 153 is an Armstrong number
pow(1,3) + pow(5,3) + pow(3,3) 
1 + 125 + 27 
153
                                               
Input: Number = 121
Output: 121 is not a Armstrong number
pow(1,3) + pow(2,3) + pow(1,3) 
1 + 8 + 1
10

Now, Let’s see the Codes:

Code 1: Use string and convert data type concept.

# given number
number = 153

# find number of digits 
numOfDigits = len(str(number))

# initialise variable
summation = 0

# looping through each 
# digit of a number
for digits in str(number) :
    
    # each digit raised to the 
    # power of number of digits
    # and sum
    summation += int(digits) ** numOfDigits
    
if summation == number :
    print("Given number",number,
          "is an Armstrong number")
else:
    print("Given number",number,
          "is not a Armstrong number") 

Output:

Given number 153 is an Armstrong number

Code 2: Use string and convert data type concept along with lambda.

# given number
number = 153

# find number of digits 
numOfDigits = len(str(number))

# create a anonymous function
# for calculating digit raised  
# to the power of number of digits
reqPower = lambda digit, number : int(digit) ** len(str(number))

# initialise variable
summation = 0

# looping through each 
# digit of a number
for digits in str(number) :
    
    # each digit raised to the 
    # power of number of digits
    # and sum
    summation += reqPower(digits, number)
    
if summation == number :
    print("Given number",number,
          "is an Armstrong number")
else:
    print("Given number",number,
          "is not a Armstrong number")  

Output:

Given number 153 is an Armstrong number

Code 3: First find number of digits then calculate power and sum it.

# given number
number = 153

# take a temporary variable temp1
temp1 = number

# initialise variable
numOfDigits = 0

# calculate number of digits
if number == 0:
    numOfDigits = 1
    
else:
    while temp1 :
        temp1 //= 10
        numOfDigits += 1

# take a temporary variable temp2
temp2 = number

# initialise variable
summation = 0

# looping through each 
# digit of a number
while temp2 :
    
    # find remainder
    remainder = temp2 % 10
    
    # each digit raised to the power 
    # of number of digits and sum
    summation += (remainder ** numOfDigits)
    
    # update the variable
    temp2 //= 10
    
if summation == number :
    print("Given number",number, 
          "is an Armstrong number")
else:
    print("Given number",number,
          "is not a Armstrong number")   

Output:

Given number 153 is an Armstrong number

Code 4: By creating user defined function for calculating number of digits and required sum.

# Create a user-defined function
# for calculating count of digits
# in a number
def countDigits(number) :
    
    # take a temporary 
    # variable temp1
    temp1 = number

    # initialise variable
    numOfDigits = 0

    # calculate number of digits
    if number == 0:
        
        # return 1
        return 1

    else:
        while temp1 :
            temp1 //= 10
            numOfDigits += 1
        
        # return the count
        return numOfDigits

# Create a user-defined function
# for calculating sum of digit raised 
# to the power of a number of digits
def findSum(number) :
    
    # take a temporary 
    # variable temp2
    temp2 = number

    # initialise variable
    summation = 0

    numOfDigits = countDigits(number)
    
    # looping through each 
    # digit of a number
    while temp2 :

        # find remainder
        remainder = temp2 % 10

        # each digit raised to the power 
        # of number of digits and sum
        summation += (remainder ** numOfDigits)

        # update the variable
        temp2 //= 10
    
    # return the final value
    return summation

# main code
if __name__ == "__main__" :
    
    # given number
    number = 153

    # check for Armstrong number
    if number == findSum(number) :
        print("Given number",number,
              "is an Armstrong number")
    else:
        print("Given number",number,
              "is not a Armstrong number")   

Output:

Given number 153 is an Armstrong number