1. 直接写出得数。
实际用时：分钟
3.7 - 2.15 =
450×10 =
$\frac{3}{4} - 0.2 =$
$\frac{1}{6} + \frac{1}{7} =$
3.14×2 =
8÷0.08 =
$\frac{1}{8} ÷ \frac{1}{5} =$
$21×\frac{1}{7} =$
600 - 325 =
0.5×20 =
$\frac{7}{11} - \frac{3}{55} =$
$10 ÷ \frac{5}{14} =$
37.5 + 62.5 =
$3.14×6^2 =$
$\frac{9}{13} ÷ 3 =$
$\frac{1}{8} - \frac{1}{9} =$
2.8×0.5 =
280 + 364 =
$8×\frac{3}{16} =$
$\frac{1}{5} + \frac{3}{4} =$
$3.14×20^2 =$
570÷19 =
$0 ÷ \frac{1}{2} =$
$\frac{3}{4} × \frac{8}{9} =$
6.8 + 4.2 =
200 -15 =
$15 ÷ \frac{1}{4} =$
$\frac{1}{2} ×14 =$
2.06×4 =
72÷24 =
$\frac{15}{4} + \frac{1}{4} =$
$\frac{5}{3} - \frac{3}{4} =$
$\frac{3}{5} ÷ \frac{9}{10} =$
$\frac{5}{8} ÷6 =$
$\frac{5}{8} ÷ \frac{8}{5} =$
$2 ÷ \frac{2}{3} =$
$\frac{18}{19} ÷ \frac{9}{19} =$
$\frac{14}{19} ÷7 =$
$\frac{21}{4} ÷7 =$
$1 ÷ \frac{9}{22} =$

1. 1.55 4500 $\frac{11}{20}$ $\frac{13}{42}$
6.28 100 $\frac{5}{8}$ 3
275 10 $\frac{32}{55}$ 28
100 113.04 $\frac{3}{13}$ $\frac{1}{72}$
1.4 644 $\frac{3}{2}$ $\frac{19}{20}$
1256 30 0 $\frac{2}{3}$
11 185 60 7
8.24 3 4 $\frac{11}{12}$
$\frac{2}{3}$ $\frac{5}{48}$ $\frac{25}{64}$ 3
2 $\frac{2}{19}$ $\frac{3}{4}$ $\frac{22}{9}$

2. 计算下面各题。
$\frac{9}{4} - ( \frac{2}{13} + \frac{1}{4} ) - \frac{11}{13}$
$8 × [0.75 + (0.5 - 0.25)]$
$415 + 248 + 85 + 52$
$3.14 × 4^2 × \frac{1}{2}$
$31.4 × 15^2 ÷ 5$
$3.14 × 2.5^2 × \frac{1}{5}$

2. 1 8 800
25.12 1413 3.925