Answer
$3240$
Work Step by Step
We are looking for the sum of the first 80 positive integers. Use the formula $S_n=\frac{n}{2}(a_1+a_n)$ with $n=80, a_1=1, a_{80}=80$:
$S_n=\frac{n}{2}(a_1+a_n)$
$S_{80}=\frac{80}{2}(1+80)$
$S_{80}=40*81$
$S_{80}=\boxed{3240}$