Question

Calculati suma: 3+6+9+...+333=

Answer 1

3+6+9+...+333=3(1+2+3+....+111)=3(111x112:2)=3x6216=18648

Answer 2

3+6+9+...333=3(1+2+3+....+111)
1+2+3+...111= 111*(111+1)/2=111*112/2=6216
6216*3=
18648