How to use val instead of var in below Scala Code

Question

How to use val instead of var in below Scala Code

var index: Long = lower
     var sum = 0L
      while(index <= upper) {
       if(number % index == 0L)
        sum += index
        index += 1L
     }
     sum

Answer 1

(lower to upper).filter(number % _ == 0).sum