简便计算:18.9*178.178+0.49-17.8*189.189

问题描述:

简便计算:18.9*178.178+0.49-17.8*189.189
十万火急!

18.9*178.178+0.49-17.8*189.189
=18.9*178*1.001-17.8*189*1.001+0.49
=0+0.49
=0.49
记住178.178=178*1.001