一、口算。
$7.63 - 2.23 =$
$6.5 + 3.45 =$
$4.5 - 3×0.3 =$
$1.68 + 4.52 =$
$35×70 =$
$2.4 - 1.15 + 1.6 =$
$2.2÷0.11 =$
$100×5.08 =$
$0.6×1.2÷0.04 =$
$252÷3 =$
$7.5×0.4 =$
$4.5×2÷4.5×2 =$
$\frac{6}{7} ÷ \frac{4}{9} =$
$\frac{5}{3} ÷ \frac{25}{9} =$
$25 - 36×\frac{2}{9} =$
$\frac{3}{5} × \frac{10}{9} =$
$\frac{1}{4} × \frac{2}{3} =$
$83×\frac{1}{83} - \frac{4}{5} =$
$\frac{6}{7} - \frac{1}{6} =$
$\frac{13}{15} - \frac{2}{5} =$
$\frac{1}{5} × \frac{1}{8} ÷ \frac{1}{10} =$
$\frac{4}{5} ÷ 8 =$
$\frac{3}{4} ÷ \frac{3}{16} =$
$\frac{3}{4} ÷ \frac{9}{10} × \frac{3}{5} =$

1. 5.4
2. 9.95
3. 3.6
4. 6.2
5. 2450
6. 2.85
7. 20
8. 508
9. 18
10. 84
11. 3
12. 4
13. $\frac{27}{14}$
14. $\frac{3}{5}$
15. 17
16. $\frac{2}{3}$
17. $\frac{1}{6}$
18. $\frac{1}{5}$
19. $\frac{29}{42}$
20. $\frac{7}{15}$
21. $\frac{1}{4}$
22. $\frac{1}{10}$
23. 4
24. $\frac{1}{2}$

二、计算下面各图形中涂色部分的面积。
1.
2.

1. $12×6=72(\mathrm{cm}^2)$
2. $8×6÷2+6×6-3.14×6^2÷4=31.74(\mathrm{cm}^2)$