Question

6+12+18+...+606 suma lui gauss repede

Answer 1

$\displaystyle 6+12+18+...+606=6(1+2+3+...+101)= \\ \\ =6 \cdot \frac{101(101+1)}{2} =6 \cdot \frac{101 \cdot 102}{2} =6 \cdot \frac{10302}{2} =6 \cdot 5151=30906$