How to make loop repeat until the sum is a single digit?

Question

Prompt: Write a program that adds all the digits in an integer. If the resulting sum is more than one digit, keep repeating until the sum is one digit. For example, the numb

Answer 1

def digit_sum(num):
    if num < 10:
        return num
    last_digit = num % 10
    num = num / 10
    return digit_sum(last_digit + digit_sum(num))

input_num = int(input("Enter an integer: "))
print("result : ",digit_sum(input_num))

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