An Armstrong number (also known as a narcissistic number, pluperfect digital invariant (PPDI), or narcissist number) is a number that is equal to the sum of its own digits each raised to the power of the number of digits.

What is an Armstrong Number?

A number is an Armstrong number if:

For a given n-digit number:

Example:

153 is an Armstrong number because:

1³ + 5³ + 3³ = 1 + 125 + 27 = 153

Checking Armstrong Number in Python

We can check whether a number is an Armstrong number using different methods.

1. Using a Loop

def is_armstrong(num):
    digits = [int(digit) for digit in str(num)]
    power = len(digits)
    total = sum(digit ** power for digit in digits)
    return total == num

# Example
num = 153
print(is_armstrong(num))  # Output: True

2. Using List Comprehension

def is_armstrong(num):
    return num == sum(int(digit) ** len(str(num)) for digit in str(num))

# Example
print(is_armstrong(9474))  # Output: True

3. Checking Armstrong Numbers in a Range

def find_armstrong_numbers(start, end):
    return [num for num in range(start, end + 1) if is_armstrong(num)]

# Example: Find Armstrong numbers between 1 and 10000
print(find_armstrong_numbers(1, 10000))

Armstrong Numbers Up to 10000

Some Armstrong numbers between 1 and 10000 are:

1, 2, 3, 4, 5, 6, 7, 8, 9, 153, 370, 371, 407, 9474

Conclusion

Armstrong numbers are an interesting mathematical concept and checking them in Python is straightforward using loops or list comprehensions. Mastering such concepts helps in understanding number properties and improving algorithmic thinking.