Question

Calculculati sumele: 4+8+12+...+1996

Answer 1

4(1+2+3+....499)=4x499x500/2=499000
seaplica sume gauss

Answer 2

$\displaystyle 4+8+12+...+1996=4(1+2+3+...+499)=4 \times \frac{499(499+1)}{2} = \\ \\ =4 \times \frac{499 \times 500}{2} =4 \times \frac{249500}{2} =4 \times 124750=499000$