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# what shall i do?

what shall i do?

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

```

First you create a while loop that runs while counter is less than the length of the array:

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

Then you add the value of the array at each index to sum and increment counter.

sum += numbers[counter]...... Hi jcorum in the video were taught to put a println in the centre . could you help me please and explain the centre part of your solution. sum += numbers[counter] many thanks Jon

sum += numbers[counter] is shorthand for sum = sum + numbers[counter].

numbers[counter] gets the value that is in the element of the numbers array that has the index value of counter. So numbers[0] gets the value at index 0, numbers[1] gets the value at index 1, etc.

When all is said and done, the variable sum will hold the sum of the values in the array, or, in 43.

Thank you for explaining that jcorum . I just get a bit confused why the tests don't always test you on exactly what you have just learnt in the videos before. I guess it's to make us think a little more and find out these things. Thanks