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Python Programs - Looping Statements

Check if a number is an Armstrong number - Python Program

Example 1 :

Python 
# Program : Armstrong number

num = int(input("Enter a number: "))
digits = list(str(num))
power = len(digits)

total = sum(int(d) ** power for d in digits)

if total == num:
    print(f"{num} is an Armstrong number.")
else:
    print(f"{num} is not an Armstrong number.")

Output

 
OUTPUT  :
Enter a number: 153
153 is an Armstrong number.

Explanation

  • Armstrong number = sum of its own digits each raised to the power of number of digits.
  • Uses list comprehension to calculate sum.
  • Works for any number of digits.

Example 2 : Advanced Program

Python 
# Program : Armstrong number

def is_armstrong(num):
    """
    Checks if a given number is an Armstrong number.

    Args:
        num: An integer.

    Returns:
        True if the number is an Armstrong number, False otherwise.
    """
    # Convert the number to a string to get the number of digits
    num_str = str(num)
    num_digits = len(num_str)
    
    armstrong_sum = 0
    # Calculate the sum of each digit raised to the power of num_digits
    for digit_char in num_str:
        digit = int(digit_char)
        armstrong_sum += digit ** num_digits
        
    return armstrong_sum == num

# Get input from the user
number_to_check = int(input("Enter a number: "))

# Check if it's an Armstrong number and print the result
if is_armstrong(number_to_check):
    print(f"{number_to_check} is an Armstrong number.")
else:
    print(f"{number_to_check} is not an Armstrong number.")

Output

 
OUTPUT  1 :
Enter a number: 153
153 is an Armstrong number.
 
OUTPUT  2 :
Enter a number: 123
123 is not an Armstrong number.

Explanation

is_armstrong(num) function:

  • Takes an integer numas input.
  • Converts numto a string (num_str) to easily determine the number of digits (num_digits) using len().
  • Initializes armstrong_sumto 0.
  • Iterates through each character (digit_char) in num_str.
  • Converts each digit_charback to an integer (digit).
  • Calculates digitraised to the power of num_digits using the ** operator and adds it to armstrong_sum.
  • Returns Trueif armstrong_sum is equal to the original num, indicating it's an Armstrong number; otherwise, returns False.

 

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