Python Program To Find Sum Of Digit Until Number Reduces To Single Digit

This Python program calculates sum of digit of a given number until number reduces to single digit.

In this program, we first read number from user. Then we use nested while loop to calculate sum of digit until number reduces to single digit. We also display sum at each step.

Python Source Code: Sum of Digit Until Number Becomes Single Digit

# Sum of digit until it reduces to single digit

# Reading number
number = int(input("Enter number: "))

# Finding sum
total_sum = 0
step = 1

condition = True

while condition:
    
    while number:
        total_sum += number%10
        number //= 10
    
    print("Step-%d Sum: %d" %(step, total_sum))
    number = total_sum
    total_sum = 0
    step += 1
    condition = number > 9

Output

Enter number: 99999999999
Step-1 Sum: 99
Step-2 Sum: 18
Step-3 Sum: 9