js-coding-challenges

Challenge 8: Sum of Digits

Write a function that takes a number as input and returns the sum of its digits. For example, if the input number is 123, the function should return 6 (1 + 2 + 3 = 6).

Answer

function sumDigits(num) {
  let sum = 0;

  // Convert the number to a string so we can loop over its digits
  const numStr = num.toString();

  // Loop over each digit in the string and add it to the sum
  for (let i = 0; i < numStr.length; i++) {
    sum += parseInt(numStr[i]);
  }

  // Return the final sum
  return sum;
}

Answer Explanation

The function takes a single argument num, which is the number to sum the digits of. Here’s what the function does:

• First, it initializes a variable sum to 0, which will hold the running total of the digit sums.
• Next, the function converts the input number to a string using the toString() method. This allows us to loop over its individual digits.
• The function then loops over each digit in the string using a for loop. For each digit, it converts the digit back to a number using parseInt() and adds it to the sum variable.
• Once the loop is finished, the function returns the final value of sum.

Here’s an example usage of the function:

console.log(sumDigits(123)); // 6
console.log(sumDigits(456)); // 15
console.log(sumDigits(789)); // 24

In this example, the function correctly sums the digits of each input number and returns the correct result.

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