nho stick nha
may tinh da thuc hien 10 vong lap.
vong lap 1:i=1;T=1;
vong lap 2:i=2;T=3;
vong lap 3:i=3;T=6;
vong lap 4:i=4; T=10;
vong lap 5:i=5;T=15;
vong lap 6:i=6;T=21;
vong lap 7:i=7;T=28;
vong lap 8:i=8;T=36;
vong lap 9:i=9;T=45;
vong lap 10:i=10;T=55;