4. 用竖式计算。
6.3×0.28= 0.174×8.9=
3.93×0.45= 13.5×0.24=
0.05×5.7= 0.81×0.14=
10.2×6.7= 5.42×3.8=

6.3×0.28=1.764
```
6.3
×0.28
-----
504
126
-----
1.764
```
0.174×8.9=1.5486
```
0.174
× 8.9
------
1566
1392
------
1.5486
```
3.93×0.45=1.7685
```
3.93
×0.45
-----
1965
1572
-----
1.7685
```
13.5×0.24=3.24
```
13.5
×0.24
-----
540
270
-----
3.240
```
0.05×5.7=0.285
```
5.7
×0.05
-----
0.285
```
0.81×0.14=0.1134
```
0.81
×0.14
-----
324
81
-----
0.1134
```
10.2×6.7=68.34
```
10.2
× 6.7
-----
714
612
-----
68.34
```
5.42×3.8=20.596
```
5.42
× 3.8
-----
4336
1626
-----
20.596
```