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# Understanding why this is the solution

OK so for this challenge I got this solution that allowed me to pass but I need a little more breakdown on why it was the solution.

while counter < numbers.count { sum += numbers[counter] counter++ }

while.swift
```let numbers = [2,8,1,16,4,3,9]
var sum = 0
var counter = 0

```

The challenge asks you to compute the sum of the numbers in the array, to get sum of the numbers you simply need to add all of them together. And that is what the code does.

```          while counter < numbers.count
```

Here you are saying that the loop should go while the counter variable is less than the number of items in the numbers array, which results in the loop running once for every number, due to the counter starting at 0.

```          sum += numbers[counter]
```

Here you are taking the sum variable and adding one of the numbers from the number array to it, the first time though the loop the first number from the array will be added, the second time though the second number and so on, this is due to the fact that you are using the counter variable as the index for the array.

```          counter++
```

Then finally you are adding one to the counter, this is needed both to ensure that the loop eventually ends and so that during the next loop you will get the next number out of the numbers array.

At the end of the loop the sum array will be equal to all of the numbers of the numbers array added together, which is what a sum is.

Thank you so much andren. I know what I was doing but just needed a further breakdown of exactly how it worked and executes the way it does. You definitely broke it down and allowed me to understand it better