199.92+2*19.99+0.01
1个回答

199.92+2*19.99+0.01

=199.92+2*19.99+2*0.01-0.01

=199.92+2*(19.99+0.01)-0.01

=199.92+2*20-0.01

=200-0.08+40-0.01

=240-0.09

=239.91