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Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and a supportive community. Start your free trial today. # While loop counting confusion

HI Can somebody please describe what y is doing in this Ruby while loop - I understand that n is iterating each by 1 each time but I can't get my head around what y is doing.

```n = 0 y = 0

while n < 251 y = n + y n = n + 1 end

puts y```

```n = 0
y = 0

while n < 251
y = n + y
n = n + 1
end

puts y
```

The line `y = n + y` adds the values of `n` and `y` together and stores the result as `y`.

In the first run of the while loop, `n` and `y` are both `0`, so `y = n + y` is `y = 0 + 0`, which sets `y` to `0`. `n` is then increased.

In the second run of the while loop, `n` has been increased to `1` and `y` is `0`, so `y = n + y` becomes `y = 1 + 0`, which sets `y` to `1`. `n` is then increased.

In the third run of the while loop, `n` has increased to `2` and `y` is `1`, so `y = n + y` is `y = 2 + 1`, which sets `y` to `3`. `n` is then increased.

In the fourth run of the while loop, `n` is `3` and `y` is `3`, so `y = n + y` is `y = 3 + 3`, which sets `y` to `6`. `n` is then increased.

In the fifth run of the while loop, `n` is `4` and `y` is `6`, so `y = n + y` is `y = 4 + 6`, which sets `y` to `10`. `n` is then increased.

...

In the 251th run of the while loop, `n` is `250` and `y` is the value of `249 + 248 + ... + 1 + 0`, so `y = n + y` is `y = 250 + 249 + 248 + ... + 2 + 1 + 0`. `n` is then increased.

In the 252nd run of the while loop, `n` is `251` and `y` is the value of `250 + 249 + ... + 1 + 0`, and `n` is not less than `251`, which ends the while loop.

The value for `y` is then printed, which is the sum of integers from `0` to `250`, which is `31375` .