18.9x178.178+0.49-17.8x189.189
4个回答

18.9x178.178+0.49-17.8x189.189

=18.9x178.178-17.8x189.189+0.49

=18.9×178×1.001—189×1.001×17.8+0.49

=18.9×178×1.001—18.9×1.001×178+0.49

=0.49