（一）直接写出得数。
$8.53 + 3.94 =$
$42 ÷ 4.2 =$
$0.13 × 7 =$
$1.68 ÷ 0.8 =$
$10 × 0.05 =$
$0.125 × 4 =$
$0.56 ÷ 28 =$
$7.5 × 0.4 =$
$6 - 2.7 =$
$8.81 - 5.57 =$
$0.36 ÷ 0.4 =$
$0.64 ÷ 0.8 =$
$10 ÷ 20 =$
$6.67 - 2 =$
$0.35 × 0.6 =$
$1.73 + 4.32 =$
$0.12 × 0.5 =$
$9.65 ÷ 0.1 =$
$0.56 ÷ 0.7 =$
$2.5 × 8 =$
$4.47 + 9.3 =$
$3.28 × 0.1 =$
$12.6 - 0.8 =$
$3.9 ÷ 0.13 =$
$6.78 - 1.4 =$
$7.2 × 0.1 =$
$0.01 × 0.1 =$
$9.5 - 0.5 =$
$9.3 ÷ 3.1 =$
$2.5 × 0.5 =$
$2.76 + 0.4 =$
$1.25 × 400 =$

$8.53 + 3.94 = 12.47$
$42 ÷ 4.2 = 10$
$0.13 × 7 = 0.91$
$1.68 ÷ 0.8 = 2.1$
$10 × 0.05 = 0.5$
$0.125 × 4 = 0.5$
$0.56 ÷ 28 = 0.02$
$7.5 × 0.4 = 3$
$6 - 2.7 = 3.3$
$8.81 - 5.57 = 3.24$
$0.36 ÷ 0.4 = 0.9$
$0.64 ÷ 0.8 = 0.8$
$10 ÷ 20 = 0.5$
$6.67 - 2 = 4.67$
$0.35 × 0.6 = 0.21$
$1.73 + 4.32 = 6.05$
$0.12 × 0.5 = 0.06$
$9.65 ÷ 0.1 = 96.5$
$0.56 ÷ 0.7 = 0.8$
$2.5 × 8 = 20$
$4.47 + 9.3 = 13.77$
$3.28 × 0.1 = 0.328$
$12.6 - 0.8 = 11.8$
$3.9 ÷ 0.13 = 30$
$6.78 - 1.4 = 5.38$
$7.2 × 0.1 = 0.72$
$0.01 × 0.1 = 0.001$
$9.5 - 0.5 = 9$
$9.3 ÷ 3.1 = 3$
$2.5 × 0.5 = 1.25$
$2.76 + 0.4 = 3.16$
$1.25 × 400 = 500$

（二）列竖式计算。
$2.15×12=$
$14.3×2.5=$
$2.5×7.15=$

$2.15×12$
```
2.15
× 12
-------
430
215
-------
25.80
```
$2.15×12=25.8$
---
$14.3×2.5$
```
14.3
× 2.5
-------
715
286
-------
35.75
```
$14.3×2.5=35.75$
---
$2.5×7.15$
```
7.15
× 2.5
--------
3575
1430
--------
17.875
```
$2.5×7.15=17.875$

（三）解决问题。
按从不同方向看到的图形，搭一个由5个小立方体组成的立体图形。判断哪个搭得对，在下面的括号里画“√”。

(√) ( )