Question

10-1.8x1.2简便算法

Answer 1

10 - 1.8 x 1.2=10 - ( 2 - 0.2) x ( 1+0.2)=10 - 2 - 2 x 0.2 + 0.2 x1 + 0.2 x 0.2=10 - 2 - 0.4 + 0.2 +0.04=8 - 0.2 +0.04=7.84