Sum of digits of a number in Python

In this post, you will learn how to calculate the sum of digits of a number using Python programming language. Such a type of question is generally asked in a programming interview. In Python, there are different ways to find the sum of digits of a number. Here, we have mentioned most of them-

Sum of digits of a number using for loop

In the given example, we have asked the user to provide the number and used the for loop to calculate the sum of digits of a number.

# Sum of digits of a number in Python
# using for loop

num = int(input("Please enter number: "))

#Initialize sum with 0
sum=0

#Loop through the digits
for x in str(num):
    sum=sum+int(x)

print("Sum of digits: ",sum)

Please enter number: 53434
Sum of digits:  19

Sum of digits of a number using while loop

In the given Python program, we asked the user to enter a number, then used the while loop to calculate the sum of digits.

# Sum of digits of a number in Python
# using for loop

num = int(input("Please enter number: "))

#Initialize sum with 0
sum=0

#Loop through the digits
while(num > 0):
    digit = num%10
    sum = sum+digit
    num = num//10
print("The total sum of digits is:",sum)

Please enter number: 63342
The total sum of digits is: 18

Sum of digits of a number using function

In the given Python program, we have defined a function to calculate the sum of digits of a number entered by the user. First, we ask the user to initialise the number, then find all the digits and calculate their sum by calling the function sumOfDigits().

# Sum of digits of a number in Python
# using function

def sumOfDigits(num):
    #Initialize sum with 0
    sum =0
    while num>0:
        sum += num%10
        num = num//10
    return sum
    
num = int(input("Please enter number: "))

print("The total sum of digits : ",sumOfDigits(num))  

Please enter number: 68579
The total sum of digits :  35

Sum of digits of a number using recursion

A recursion function is a function that is called by itself. In the given example, we use the recursion function to find the sum of digits of a given number. A recursion function continues until some condition is met to prevent it. That's why we use the if else statement to break the infinite recursion.

# Sum of digits of a number in Python
# using function

def sumOfDigits(n):
    # Check if n is less than 10, if true return n
    if n< 10:
        return n
    else:
        # divide the number by 10 
        # and calculate the remainder
        return n%10 + sumOfDigits(n//10)

# Input from the user
num = int(input("Please enter number: "))

# Call function and pass input as a parameter
print("The total sum of digits : ",sumOfDigits(num))  

Please enter number: 865577
The total sum of digits :  38

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