# Loop why result is 36 explain please

explain someone why result of program is value 36? In java I'm just beginner.

``````public static void main(String[] args) {

int sum = 0;
for (int i = 1; i < 9 ; i++) {

sum+=i;
}
System.out.println(sum);

}
``````

The loop is computing the sum of an arithmetic series, with values from 1 to 8 inclusive. Using the standard formula, this is the number of terms (8) times the average of the first and last values (1+8)/2, which works out as 36.

Let's look at one iteration at a time:

First, we start with `sum = 0`.

The first iteration we have `i = 1`. The value of `sum`, which is zero, becomes 1 when we do `sum += 1`.

The second iteration we have `i = 2`. The value of `sum`, which is one, becomes 3 when we do `sum += 2`.

The third iteration we have `i = 3`. The value of `sum`, which is three, becomes 6 when we do `sum += 3`.

The fourth iteration we have `i = 4`. The value of `sum`, which is six, becomes 10 when we do `sum += 4`.

The fifth iteration we have `i = 5`. The value of `sum`, which is ten, becomes 15 when we do `sum += 5`.

The sixth iteration we have `i = 6`. The value of `sum`, which is fifteen, becomes 21 when we do `sum += 6`.

The seventh iteration we have `i = 7`. The value of `sum`, which is twenty-one, becomes 28 when we do `sum += 7`.

The eighth iteration we have `i = 8`. The value of `sum`, which is twenty-eight, becomes 36 when we do `sum += 8`.

We have now completed the for loop since the next value for `i` would be 9 and we specified the loop would only continue so long as `i < 9`. At this point, the value of `sum` is 36.