Question

sa-mi calculati suma lui gauss
4+8+12+.....+2000

Answer 1

$\displaystyle 4+8+12+...+2000=4(1+2+3+...+500)=4 \times \frac{500(500+1)}{2} = \\ \\ =4 \times \frac{500 \times 501}{2} =4 \times \frac{250500}{2} =4 \times 125250=501000$