一、口算。
1.72 - 0.4 =
0.25 × 4 =
3.05 × 100 =
6.45 + 5.5 =
3.5 ÷ 0.7 =
8.1 ÷ 2.7 =
3.4 × 20 =
6.02 - 5.94 =
2.22 + 1.88 =
8.8 ÷ 0.4 =
5.25 ÷ 0.5 =
0.65 × 2 =
27 ÷ $\frac{3}{8}$ =
$\frac{4}{5} ÷ \frac{2}{7}$ =
24 - 24 × $\frac{5}{6}$ =
$\frac{4}{7} ÷ 6$ =
$\frac{7}{30} + 0.25$ =
5 × $(1 - \frac{3}{8})$ =
0.3 - $\frac{1}{4}$ =
$\frac{3}{10} ÷ \frac{3}{5}$ =
560 × $(1 - \frac{2}{7})$ =
$\frac{5}{3} ÷ \frac{5}{4}$ =
$\frac{5}{12} × 1.6$ =
72 - 72 × $\frac{4}{9}$ =

1. 32
2. 1
3. 305
4. 11.95
5. 5
6. 3
7. 68
8. 0.08
9. 4.1
10. 22
11. 10.5
12. 1.3
13. 72
14. $\frac{14}{5}$
15. 4
16. $\frac{2}{21}$
17. $\frac{29}{60}$
18. $\frac{25}{8}$
19. $\frac{1}{20}$
20. $\frac{1}{2}$
21. 400
22. $\frac{4}{3}$
23. $\frac{2}{3}$
24. 40

二、计算下面各题，能简算的要简算。
$18÷\frac{3}{7}÷\frac{14}{3}$
$\frac{8}{15}÷9+\frac{1}{9}×\frac{7}{15}$
$5-\frac{14}{75}÷\frac{2}{15}-\frac{3}{5}$
$0.9+9.9+99.9$
$7.25×0.4+12.75×0.4$
$(39-11.4)÷(13.8÷0.6)$

1. 9
2. $\frac{1}{9}$
3. 3
4. 110.7
5. 8
6. 1.2