一、口算。
$24.5×0.2=$
$24.5 - 4.05=$
$10.2×0.2=$
$15×0.8=$
$320÷0.16=$
$0.4 - 0.04=$
$50×2.4=$
$3 - 0.13=$
$12.5×200=$
$4.32÷0.08=$
$2.4×0.3=$
$2.7 + 8.3=$
$\frac{5}{7}×\frac{21}{25}=$
$9÷\frac{6}{7}=$
$\frac{3}{7}×21=$
$\frac{4}{15}÷\frac{8}{5}=$
$\frac{8}{9} - \frac{2}{3}=$
$0.8÷\frac{3}{50}=$
$2×\frac{2}{3}=$
$\frac{7}{27}÷\frac{5}{9}=$
$\frac{7}{8} + \frac{1}{6}=$
$\frac{1}{6} + \frac{1}{9}=$
$\frac{2}{13}÷\frac{8}{13}=$
$\frac{8}{3}×0.3=$

1. 4.9
2. 20.45
3. 2.04
4. 12
5. 2000
6. 0.36
7. 120
8. 2.87
9. 2500
10. 54
11. 0.72
12. 11
13. $\frac{3}{5}$
14. $\frac{21}{2}$
15. 9
16. $\frac{1}{6}$
17. $\frac{2}{9}$
18. $\frac{40}{3}$
19. $\frac{4}{3}$
20. $\frac{7}{15}$
21. $\frac{25}{24}$
22. $\frac{5}{18}$
23. $\frac{1}{4}$
24. $\frac{4}{5}$

二、计算下面各题，能简算的要简算。
$56×(\dfrac{4}{7}+\dfrac{5}{8}-\dfrac{3}{4})$
$(\dfrac{3}{7}+\dfrac{3}{5})×7+\dfrac{4}{5}$
$\dfrac{2}{7}×\dfrac{3}{4}÷\dfrac{2}{7}×\dfrac{3}{4}$
$7.85-(2.85+0.37)$
$2.5×8.1×0.4÷0.3$
$(71.2-71.2×0.9)÷0.25$

1. 25
2. 8
3. $\frac{9}{16}$
4. 4.63
5. 27
6. 28.48