Answer
$5050$
Work Step by Step
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 $a_{50}=1+1(100-1)=100$
Then, our first (1) equation becomes: $S_{100}=\dfrac{100}{2}(1+100)=\dfrac{100}{2}(101)=5050$
