[tex]\displaystyle\bf\\S=1+3+5+7+...+845\\\\\text{Calculam numarul de termeni:}\\n=\frac{845-1}{2}+1=\frac{844}{2}+1=422+1=423~de~termeni\\\\Formula~lui~Gauss: \\S=\frac{n(ultimul~termen+primul~termen)}{2}\\\\=\frac{423(845+1)}{2}=\frac{423(846)}{2}=423\times423=\boxed{\bf423^\b{\bf2}}[/tex]
