Python check armstrong number using for loop

In this post, you will learn how to write program in Python to check whether a given number is Armstrong or not.

An Armstrong number (or narcissistic number) for a given number of digits is a number that is equal to the sum of its own digits each raised to the power of the number of digits.

Formula to check Armstrong number

A positive number of n digits is called an Armstrong number of order n.

abcde.... = aⁿ + bⁿ + cⁿ + dⁿ + eⁿ +

For example, to check if 153 is an Armstrong number:

The number of digits, n, is 3.
Calculate 1³ + 5³ + 3³.
1³ = 1,5³ = 125, 3³ = 27.
Sum these values: 1 + 125 + 27 = 153.

Here's how you can check if a number is an Armstrong number using a for loop in Python:

# Function to check if a number is an Armstrong number
def is_armstrong_number(num):
    # Convert the number to a string to easily iterate over its digits
    num_str = str(num)
    num_digits = len(num_str)
    sum_of_powers = 0
    
    # Iterate over each digit
    for digit in num_str:
        sum_of_powers += int(digit) ** num_digits
    
    # Check if the sum of the powers of its digits equals the original number
    return sum_of_powers == num

# Example usage
num = 153
if is_armstrong_number(num):
    print(f"{num} is an Armstrong number.")
else:
    print(f"{num} is not an Armstrong number.")

Output of the above code:

When you run this code with num = 153, it will output:

153 is an Armstrong number.

Code Explanation:

The function is_armstrong_number takes an integer num as input.
It converts num to a string to easily iterate over its digits.
It calculates the number of digits in num using len(num_str).
It initializes sum_of_powers to 0.
It uses a for loop to iterate over each digit in the string representation of num.
For each digit, it raises the digit to the power of the number of digits and adds the result to sum_of_powers.
Finally, it checks if sum_of_powers equals the original number num and returns the result.