巧算:399.6*9-1998*0.8
问题描述:
巧算:399.6*9-1998*0.8
答
=(400-0.4)*9-(2000-2)*0.8
=400*9-0.4*9-2000*0.8+2*0.8
=3600-3.6-1600+1.6
=2000-2
=1998