Question

1+2+3...+20
va rog repede

Answer 1

1+2+3+...+20
Formula pentru Suma lui Gauss:n*(n+1):2
1+2+3+...+20=20*21:2=10*21=210

Answer 2

$\displaystyle 1+2+3+...+20= \frac{20(20+1)}{2} = \frac{20 \times 21}{2} = \frac{420}{2} = 210$