Find number of digits in range of numbers

How many digits does it take to assign numbers to 283 employees using numbers from 1 through 283?

function findNumberOfDigits(n){
  let count = 0
  for(let i=1; i<=n; i++){
    // ((''+i)).length => count number of digits
    count += ((''+i)).length
  }
  return count
}

This function returns the number of digits from 1 to n. n should be entered by the user.

For example: if n=12, it returns 15. From 1 to 12 (1,2,3,4,5,6,7,8,9,10,11,12), there is 15 digits.

@ncutixavier