Sum of odd integers

If you aren't familiar with AP, refer the last of the solution.

Number of terms in an AP $=\dfrac{l-a}{d}+1$

In this case, $n=\dfrac{659-17}{2}+1=322$

Sum of terms of AP $=\dfrac{n}{2}(a+l)$ Here, sum $=\dfrac{322}{2}(17+659)=108836$

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Note:

First term of an AP $=a$

Last term of an AP $=l$

Difference between 2 consecutive terms $=d$

Number of terms in an AP $=n$