谁知道0.21*6.4+0.42*1.8的简便计算
问题描述：
谁知道0.21*6.4+0.42*1.8的简便计算
答
0.21*6.4+0.42*1.8
=0.21*（6+0.4）+0.42*（2-0.2）
=0.21*6+0.21*0.4+0.42*2-0.42*0.2
=1.26+0.084+0.84-0.084
=2.1
答
0.21*6.4+0.21*2*1.8=0.21*(6.4+3.6)=2.1
答
0.21*6.4+0.24*1.8
=0.21*6.4+0.21*2*1.8
=0.21*6.4+0.21*3.6
=0.21*（6.4+3.6）
=0.21*10
=2.1