Question

用简便方法计算下面各题2.2×2.5 1.8×2.5

Answer 1

用简便方法计算下面各题2.2×2.5 1.8×2.5

解：

1.   2.2×2.5

   =（2+0.2）x2.5

   =2x2.5+0.2x2.5

   =5+0.5

   =5.5

2.  1.8×2.5

   =（2-0.2）x2.5

   =5-0.5

   =4.5

Answer 2

2.2×2.5+1.8×2.5
=2.5×(2.2+1.8)
=2.5×4
=10

Answer 3

2.2×2.5+1.8×2.5
=(2.2+1.8)×2.5
=4×2.5
=10

Answer 4

2.2×2.5-1.8×2.5
=（2.2-1.8）x2.5
=0.4x2.5
=1