用简便计算5.49x0.38 4.05+37.85 2.96x40怎样计算

Question

如题所述

Answer 1

5.49x0.38
=（5.5-0.01）×0.38
=5.5×0.38-0.01×0.38
=2.09-0.0038
=2.0862

4.05+37.85
=（4+37）+（0.05+0.85）
=41+0.9
=41.9

2.96x40
=（3-0.04）×40
=3×40-0.04×40
=120-1.6
=118.4