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

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

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

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

简便计算:18.9*178.178+0.49-17.8*189.189
=18.9*178*1.001-17.8*189*1.001+0.49
=189*17.8*1.001-17.8*189*1.001+0.49
=0.49

18.9*178.178+0.49-17.8*189.189
=18.9*178+18.9*0.178-17.8*189-17.8*0.189+0.49
=18.9*178-178*18.9+18.9*0.178-0.178*18.9+0.49
=0.49