一、口算。
$0.84÷2.1=$
$2.82+1.78=$
$3.4÷0.17=$
$1.08×50=$
$1.9+10.01=$
$2.48÷0.8=$
$89÷2=$
$623-598=$
$66.26+20.74=$
$0.36×2=$
$7.32×4=$
$5.17-2.69=$
$\frac{1}{3}×\frac{3}{10}=$
$\frac{7}{12}+\frac{3}{4}=$
$\frac{7}{12}-\frac{1}{4}=$
$\frac{4}{5}÷\frac{2}{3}=$
$\frac{5}{3}×\frac{1}{3}=$
$\frac{5}{6}×\frac{7}{10}=$
$1÷\frac{5}{6}=$
$\frac{3}{4}×\frac{2}{9}=$
$0.25÷\frac{9}{10}=$
$\frac{2}{17}÷\frac{6}{17}=$
$\frac{4}{5}×0.25=$
$\frac{5}{8}×\frac{4}{15}=$

1. 0.4
2. 4.6
3. 20
4. 54
5. 11.91
6. 3.1
7. 44.5
8. 25
9. 87
10. 0.72
11. 29.28
12. 2.48
13. $\frac{1}{10}$
14. $\frac{4}{3}$
15. $\frac{1}{3}$
16. $\frac{6}{5}$
17. $\frac{5}{9}$
18. $\frac{7}{12}$
19. $\frac{6}{5}$
20. $\frac{1}{6}$
21. $\frac{5}{18}$
22. $\frac{1}{3}$
23. $\frac{1}{5}$
24. $\frac{1}{6}$

二、计算下面各题，能简算的要简算。
$(\frac{2}{3} + \frac{1}{4} ÷ \frac{3}{4}) × \frac{1}{4}$
$\frac{5}{44} ÷ [ \frac{5}{8} ÷ ( \frac{14}{3} - \frac{1}{2} ) ]$
$\frac{8}{7} × [ 0.75 - ( \frac{9}{16} - \frac{1}{4} ) ]$
$3.28 ÷ 4 ÷ (0.67 - 0.42)$
$168.1 ÷ (4.3 × 2 - 0.4)$
$0.56 × 8.3 + 0.44 × 8.3$

1. $\frac{1}{4}$
2. $\frac{25}{33}$
3. $\frac{1}{2}$
4. 3.28
5. 20.5
6. 8.3