Question

Cat face 1+2+4+...+512 va rog ajutatima

Answer 1

1+2+4+...+512 =
=1+2(1+2+...256)
=1+2x256x257/2
=1+65792
=65793

Answer 2

 $\displaystyle S=1+2+4+6+...+512 \\ \\ S=1+2(1+2+3+...+256) \\ \\ S=1+2\times \frac{256(256+1)}{2} \\ \\ S=1+256\times 257=65793$