Question

What is the sum of a 54–term arithmetic sequence where the first term is 6 and the last term is 377?

Answer 1

$S_n=\dfrac{(a_1+a_n)n}{2}\\--------------------\\a_1=6;\ n=54;\ a_n=a_{54}=377\\\\subtitute\\\\S_{54}=\dfrac{(6+377)\cdot54}{2}=483\cdot27=13,041\\\\Answer:\boxed{S_{54}=13,041}$