Repeated sum of Number’s digits in JavaScript

We are required to write a JavaScript function that recursively sums up the digits of a number until it reduces to a single digit number.

We are required to do so without converting the number to String or any other data type.

Therefore, let’s write the code for this function −

Example

The code for this will be −

const num = 546767643; const sumDigit = (num, sum = 0) => {    if(num){       return sumDigit(Math.floor(num / 10), sum + (num % 10));    }    return sum; }; const sumRepeatedly = num => {    while(num > 9){       num = sumDigit(num);    };    return num; }; console.log(sumRepeatedly(num));

Output

The output in the console will be −

3