Question

72.2X0.84+0.16X2.5的简便方法？

Answer 1

72.2X0.84+0.16X2.5
=60.648+0.4
=61.048。

Answer 2

答：可以这样做0.84=1-0.16，所以如下
72.2*0.84+0.16*2.5
=72.2*（1-0.16）+0.16*2.5
=72.2-72.2*0.16+0.16*2.5
=72.2-（72.2-2.5）*0.16
=72.2-（70-0.3）*0.16
=72.2-70*0.16+0.3*0.16
=72.2-11.2+0.048
=61+0.048
=61.048。
所以答案是61.048。

Answer 3

72.2×0.84+0.16×2.5
＝72.2×0.84+0.4×0.4×2.5
＝72.2×0.84+0.4
算到这就没有简便方法了

Answer 4

72.2x（1-0.16）+0.16x0.25=72.2-72.2x0.16+2.5x0.16=72.2-（72.2-2.5）x0.16=72.2-（70+2.2-2.5）x0.16=72.2-70x0.16+0.3x0.16=72.2+0.048-7x1.6=72.248-7-4.2=65.248-4.2=61.048