用简便计算,3.14*1.9+31.4*8.1

问题描述:

用简便计算,3.14*1.9+31.4*8.1

3.14*1.9+31.4*0.81
=31.4*0.19+31.4*0.81
=31.4*(0.19+0.81)
=31.4