Try this.

```
for (int i=1; i < n; i++) {
double calculations = Math.pow(-1,i + 1) / (2 * (i-1) + 1);
sum += calculations;
}
System.out.println(4*sum);
```

- First, the first denominator must be 1 so
`2*(i-1) + 1 = 0 + 1 = 1.`

- Second, remember that the series computes
`pi/4`

so you need to mutiply by`4`

.

Here is a suggestion. Instead of doing the Math.pow overhead, just use a ternery operator (`?:`

)to see if `i`

is even or odd and change the sign accordingly.

```
double calculations = ((i % 2) == 0 ? -1. : 1.) / (2.*(i-1)+1);
```

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