Question

2.5*18.6*0.394+2.14*1.86*39.4

Answer 1

2.5×18.6×0.394+2.14×1.86×39.4
=18.6×3.94×（0.1×2.5+2.14）
=18.6×3.94×（2.14+0.25）
=18.6×4×2.39-18.6×0.06×2.39
=74.4×2.39-18.6×0.06×2.39
=75×2.39-0.6×2.39-18.6×0.06×2.39
=75×2.4-75×0.01-0.06×2.39×（10+18.6）
=75×4×0.6-0.75-0.1434×28.6
=300×0.6-（0.75+0.1434×30）+0.1434×1+0.1434×0.4
=180+0.1434+0.05736-（0.75+4.302）
=180.20076-5.052
=185.14876

Answer 2

＝2.5*1.86*3.94+21.4*1.86*3.94
＝1.86*3.94*（2.5+21.4）
＝7.3284*23.9
＝175.14876