Python Program to Find the Sum of Digits of a Number

The sum of digits of a number is the total sum of all its individual digits. For example, the sum of digits of 123 is:

In this tutorial, we will write a Python program to calculate the sum of digits of a given number.

Python Program to Find the Sum of Digits

# Function to calculate sum of digits
def sum_of_digits(num):
    total = 0
    while num > 0:
        total += num % 10  # Extract the last digit and add to total
        num //= 10  # Remove the last digit
    return total

# Taking user input
number = int(input("Enter a number: "))

# Calculating and displaying the sum of digits
result = sum_of_digits(abs(number))  # Using abs() to handle negative numbers
print(f"Sum of digits of {number} is: {result}")

How It Works

1. Extract the last digit using num % 10.
2. Add it to the sum and remove the last digit using num //= 10.
3. Repeat until all digits are processed.
4. The result is the sum of all digits.

Output

Enter a number: 1234
Sum of digits of 1234 is: 10

Using Recursion

We can also solve this problem using recursion.

# Recursive function to find sum of digits
def sum_of_digits_recursive(num):
    if num == 0:
        return 0
    return (num % 10) + sum_of_digits_recursive(num // 10)

# Taking user input
number = int(input("Enter a number: "))

# Calculating and displaying the sum of digits
result = sum_of_digits_recursive(abs(number))
print(f"Sum of digits of {number} is: {result}")