18.9*178.178+0.49-17.8*189.18 简算
问题描述：
18.9*178.178+0.49-17.8*189.18
简算
答
18.9*178.178+0.49-17.8*189.18
=3367.5642+0.49-3367.404
=3368.0542-3367.404
=0.6502
答
=18.9*178.178+0.49-17.8*（189+0.18）
=18.9（178.178-178）+0.49-17.8*0.18
=18.9*0.178+0.49-17.8*0.18
=0.178*（18.9-18）+0.49
=0.178*0.9+0.49
=0.6502