Question

Calculați 1+2+3+...+2010+2011

Answer 1

Aplicam  Suma Gauss, care este [n × (n+1)] / 2
[2011×  (2011+1)] / 2=
(2011×2012)/2=
4046132 : 2 =
2 023 066

Answer 2

$\bold{1+2+3+...+2010+2011= \frac{2011 \cdot (2011+1)}{2} }= \\ =\bold{ \frac{2011 \cdot 2012}{2} = \frac{4 \ 046 \ 132}{2} }=\boxed{\bold{2 \ 023 \ 066}}$