Question

formula lui gaoss a=1+2+3+...79+80

Answer 1

a=1+2+3+..+79+80
a=$\frac{80*81}{2}$
a=$\frac{6480}{2}$
s=3240

Answer 2

a=((1+80)x80):2
a=(81x80):2
a=6480:2
a=3240