一、口算。
650 + 56 =
630 ÷ 21 =
5.9 - 5.1 + 6.2 =
495 - 19 =
8.8 × 0.5 =
7.2 × 0.8 × 2.5 =
2 × 398 =
1.13 - 0.14 =
5.6 ÷ 0.7 ÷ 0.4 =
0.47 + 0.6 =
0.72 ÷ 0.9 =
(23.7 - 7.5) × 2 =
0.72 × $\frac{5}{9}$ =
$\frac{5}{12}$ × $\frac{3}{20}$ =
$\frac{4}{9}$ - $\frac{2}{7}$ + $\frac{5}{9}$ =
$\frac{2}{3}$ + $\frac{1}{4}$ =
$\frac{3}{2}$ ÷ $\frac{5}{2}$ =
25 × $\frac{5}{6}$ × 4 =
6 × $\frac{5}{12}$ =
$\frac{8}{5}$ - $\frac{9}{10}$ =
$\frac{3}{4}$ ÷ 3 × $\frac{3}{4}$ ÷ 3 =
$\frac{6}{7}$ ÷ $\frac{10}{13}$ =
0.95 - $\frac{1}{20}$ =
$\frac{5}{4}$ × 8 + 8 × $\frac{1}{4}$ =

1. 706
2. 30
3. 7
4. 476
5. 4.4
6. 14.4
7. 796
8. 0.99
9. 20
10. 1.07
11. 0.8
12. 32.4
13. $\frac{2}{5}$
14. $\frac{1}{16}$
15. $\frac{5}{7}$
16. $\frac{11}{12}$
17. $\frac{3}{5}$
18. $\frac{250}{3}$
19. $\frac{5}{2}$
20. $\frac{7}{10}$
21. $\frac{1}{16}$
22. $\frac{39}{35}$
23. $\frac{9}{10}$
24. 12

二、计算下面各题，能简算的要简算。
$999\frac{8}{9} + 99\frac{8}{9} + 9\frac{8}{9}$
$\frac{7}{4} - \frac{5}{16} × \frac{4}{3} - \frac{7}{12}$
$( \frac{2}{3} + \frac{6}{7} × \frac{7}{24} ) ÷ \frac{11}{32}$
$0.8 × [ (5 - 0.68) ÷ 1.2 ]$
$17.64 ÷ 4.9 + 6.73 + 0.37$
$19.8 - 0.6 × 0.6 - 0.64$

1. $1109\frac{2}{3}$
2. $\frac{3}{4}$
3. $\frac{8}{3}$
4. 2.88
5. 10.7
6. 18.8