How do you find the sum of the digits of a number in python?

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Given a number and the task is to find sum of digits of this number in Python. 
Examples: 
 

Input : n = 87 
Output : 15 
Input : n = 111 
Output : 3

 
Below are the methods to sum of the digits. 
Method-1: Using str() and int() methods.: The str() method is used to convert the number to string. The int() method is used to convert the string digit to an integer. 

Convert the number to string and iterate over each digit in the string and after converting each digit to integer and add to the sum of the digits in each iteration. 

Python3

def getSum(n):

    sum = 0

    for digit in str(n): 

      sum += int(digit)      

    return sum

n = 12345

print(getSum(n))

Output:

15

Method-2: Using sum() methods.: The sum() method is used to sum of numbers in the list.

Convert the number to string using str() and strip the string and convert to list of number using strip() and map() method resp. Then find the sum using the sum() method.

Python3

def getSum(n):

    strr = str(n)

    list_of_number = list(map(int, strr.strip()))

    return sum(list_of_number)

n = 12345

print(getSum(n))

Output:

15

Method-3: Using General Approach: 

• Get the number
• Declare a variable to store the sum and set it to 0
• Repeat the next two steps till the number is not 0
• Get the rightmost digit of the number with help of remainder ‘%’ operator by dividing it with 10 and add it to sum.
• Divide the number by 10 with help of ‘//’ operator
• Print or return the sum

A. Iterative Approach:

Python3

def getSum(n):

    sum = 0

    while (n != 0):

        sum = sum + (n % 10)

        n = n//10

    return sum

n = 12345

print(getSum(n))

Output:

15

B. Recursive Approach:

Python3

def sumDigits(no):

    return 0 if no == 0 else int(no % 10) + sumDigits(int(no / 10)) 

n = 12345

print(sumDigits(n))

Output:

15

This is a Python Program to find the sum of digits in a number.

Problem Description

The program takes in a number and finds the sum of digits in a number.

Problem Solution

1. Take the value of the integer and store in a variable.
2. Using a while loop, get each digit of the number and add the digits to a variable.
3. Print the sum of the digits of the number.
4. Exit.

Program/Source Code

Here is the source code of the Python Program to find the sum of digits in a number. The program output is also shown below.

 
n=int(input("Enter a number:"))
tot=0
while(n>0):
    dig=n%10
    tot=tot+dig
    n=n//10
print("The total sum of digits is:",tot)

Program Explanation

1. User must first enter the value and store it in a variable.
2. The while loop is used and the last digit of the number is obtained by using the modulus operator.
3. The digit is added to another variable each time the loop is executed.
4. This loop terminates when the value of the number is 0.
5. The total sum of the number is then printed.

Runtime Test Cases

 
Case 1:
Enter a number:1892
The total sum of digits is: 20
 
Case 2:
Enter a number:157
The total sum of digits is: 13

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