Question

Calculati suma 2+4+6+...+100=

Answer 1

2*(1+2+3+.......+50)= 2*(1+50)*50:2=2*51*25=51*50=2550

Answer 2

2+4+6+..................+94+96+98+100  
poti face 2+98=100 ,4+96=100 ,6+94=100
ai 100+100+100.....de 48 de ori + 100 care era +50 care nu are pereche.
100×49=4900+50=4950
:) :) :)