## Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

$S_{250}=31375$
The first n term of an arithmetic sequence can be calculated as: $S_n=\frac{n}{2}(a_1+a_n)$ We have to find the sum of the first 250 natural numbers. $a_1=1$ $a_{250}=250$ Therefore we can substitute in the formula of the sum, and we get: $S_{250}=\frac{250}{2}(1+250))=125\times251=31375$