一、口算。
1110 - 111 =
1.25 × 0.008 =
32 ÷ 0.5 =
640 ÷ 20 =
12 - 3.1 =
210 × 30 =
1.24 + 9.8 =
2.5 × 0.08 =
2500 ÷ 125 =
0.75 ÷ 0.05 =
293 + 260 =
20 × 0.9 =
3.6 + 0.12 =
40 × 60 =
3.2 - 1.6 =
$\frac{5}{9} ÷ \frac{2}{3} =$
$\frac{1}{3} + \frac{5}{6} =$
$\frac{3}{8} - \frac{1}{6} =$
$\frac{5}{12} ÷ \frac{5}{8} =$
$\frac{8}{15} ÷ \frac{8}{3} =$
$\frac{3}{8} ÷ \frac{5}{32} =$
$125 × \frac{4}{25} =$
$\frac{1}{2} ÷ \frac{3}{4} =$
$\frac{5}{12} + \frac{1}{4} =$

999
0.01
64
32
8.9
6300
11.04
0.2
20
15
553
18
3.72
2400
1.6
$\frac{5}{6}$
$\frac{7}{6}$
$\frac{5}{24}$
$\frac{2}{3}$
$\frac{1}{5}$
$\frac{12}{5}$
20
$\frac{2}{3}$
$\frac{2}{3}$

二、想一想，填一填。
1. $5068=(\quad)×5+(\quad)×6+(\quad)×8$
2. $404.04=(\quad)×4+(\quad)×4+(\quad)×4$
3. $62.097=(\quad)×6+(\quad)×2+(\quad)×9+(\quad)×7$
4. $2.6=0.1×(\quad)=0.01×(\quad)=0.001×(\quad)$

1. 1000 10 1
2. 100 1 0.01
3. 10 1 0.01 0.001
4. 26 260 2600

5. $\frac{5}{8} = (\quad) × 5 = (\quad) × 10 = (\quad) × 20$

$\frac{1}{8}$ $\frac{1}{16}$ $\frac{1}{32}$

6. $\frac{7}{12}=(\quad)×7=(\quad)×21=(\quad)×70$

$\frac{1}{12}$ $\frac{1}{36}$ $\frac{1}{120}$