## Precalculus (6th Edition) Blitzer

$10100$
Formula to calculate the sum of an arithmetic sequence is: $S_n=\dfrac{n}{2}(a_1+a_n)$ ...(1) Here, $a_1:$ First term and $d=$ common difference Since, we have $d=1$ and $a_{100}=1+1(100-1)=100$ Then, our first (1) equation becomes: $S_{100}=\dfrac{100}{2}(2+200)=\dfrac{100}{2}(202)=10100$