Răspuns :
2+4+6+...+200=2(1+2+3+...+100)=
=2*100*101/2=100*101=10100
=2*100*101/2=100*101=10100
2+4+6+8+...+200=
2(1+2+3+...+100)=
2 x (100x101)\2=
2 x 10100\2=
2 x 5050=
=10100
Succes!