12+56+1112+1920+2930+…+97019702+98999900.

12+56+1112+1920+2930+…+97019702+98999900.

12+56+1112+1920+2930+…+97019702+98999900=(1-12)+(1-16)+(1-112)+…+(1-19900)=1×99-(12+16+112+…+19900),=99-(11×2+12×3+13×4…+199×100),=99-(1-12+12-13+13−14+…+199-1100),=99-(1-1100),=99-99100,=981100.