Medium

# Get the Sum of Digits in a number till it become a single digit

Objective - Given a number, Write a program to get the sum of digits in a number till it become a single digit.

Example:

```N = 999 -> 9+9+9 = 27-> 2+7 = 9
N = 789 -> 7+8+9= 24-> 2+4 = 6```

Approach:

Recursion-

• Find the sum of all digits.
• Make a recursive call with the sum calculated in step 1.
• If the number is less than 10, return the number.
• See the code and click on the run code button for more understanding.

Code:

Output:

```Sum of digits in a number 12345 till it become a single digit: 6
Sum of digits in the number 999 till it becomes a single digit: 9
```

Tricky Approach:

• If number is 0, return 0.
• Find remainder of number with 9. (number%9).
• If remainder is 0, return 9 else return the remainder.

Code:

Output:

```Sum of digits in a number 12345 till it become a single digit: 6
Sum of digits in a number 999 till it become a single digit: 9
Sum of digits in a number 111 till it become a single digit: 3
```