Question

{{[(1+2+ 3+...+100):1010 )

Answer 1

[(100*101):2]:1010=5050:1010=5

Answer 2

$\displaystyle (1+2+ 3+...+100):1010 = \\\\ \text{Aplicam gaus in prima paranteza} \\ \\ \frac{n(n+1)}{2} = \frac{100(100+1)}{2}= \frac{100\cdot101}{2}=5050 \\ \\\\ 5050:1010 = 5$