Răspuns :
10+20+30+...+120
simplificam ecuatia prin 10 si avem
10 x (1+2+3...+12)=10 x (12 x 13 /2)
=10 x (156/2)
=10 x78
=780
simplificam ecuatia prin 10 si avem
10 x (1+2+3...+12)=10 x (12 x 13 /2)
=10 x (156/2)
=10 x78
=780