一、口算。
0.19×3=
0.81×60=
0.08×8=
1.2×500=
2.3×4=
2.5×400=
8.5×4=
0.25×30=
0.01×120=
5.6×8=
4.6×5=
0.96×5=
0.2×808=
1.52×2=
1.1×90=
$\frac{2}{5}×\frac{1}{4}=$
$\frac{1}{8}×\frac{6}{7}=$
$\frac{3}{8}×\frac{8}{5}=$
$\frac{9}{10}×\frac{2}{3}=$
$\frac{3}{4}×\frac{8}{27}=$
$\frac{5}{22}×2=$
$\frac{11}{18}×\frac{9}{5}=$
$\frac{6}{7}×\frac{3}{2}=$
$\frac{9}{8}×\frac{3}{4}=$

1. 0.19×3=0.57
2. 0.81×60=48.6
3. 0.08×8=0.64
4. 1.2×500=600
5. 2.3×4=9.2
6. 2.5×400=1000
7. 8.5×4=34
8. 0.25×30=7.5
9. 0.01×120=1.2
10. 5.6×8=44.8
11. 4.6×5=23
12. 0.96×5=4.8
13. 0.2×808=161.6
14. 1.52×2=3.04
15. 1.1×90=99
16. $\frac{2}{5}×\frac{1}{4}=\frac{1}{10}$
17. $\frac{1}{8}×\frac{6}{7}=\frac{3}{28}$
18. $\frac{3}{8}×\frac{8}{5}=\frac{3}{5}$
19. $\frac{9}{10}×\frac{2}{3}=\frac{3}{5}$
20. $\frac{3}{4}×\frac{8}{27}=\frac{2}{9}$
21. $\frac{5}{22}×2=\frac{5}{11}$
22. $\frac{11}{18}×\frac{9}{5}=\frac{11}{10}$
23. $\frac{6}{7}×\frac{3}{2}=\frac{9}{7}$
24. $\frac{9}{8}×\frac{3}{4}=\frac{27}{32}$

二、先想想积是几位小数，再计算。
$0.06×0.8=\frac{6}{( )}×\frac{8}{( )}=\frac{48}{( )}=( )$
$0.5×1.7=\frac{( )}{10}×\frac{( )}{10}=\frac{( )}{100}=( )$
$7×0.04=7×\frac{( )}{( )}=\frac{7×( )}{( )}=\frac{( )}{( )}=( )$
$3.9×0.02=\frac{( )}{( )}×\frac{( )}{( )}=\frac{( )}{( )}=( )$
$0.24×0.09=\frac{( )}{( )}×\frac{( )}{( )}=\frac{( )}{( )}=( )$

1. $0.06×0.8=\frac{6}{100}×\frac{8}{10}=\frac{48}{1000}=0.048$
2. $0.5×1.7=\frac{5}{10}×\frac{17}{10}=\frac{85}{100}=0.85$
3. $7×0.04=7×\frac{4}{100}=\frac{7×4}{100}=\frac{28}{100}=0.28$
4. $3.9×0.02=\frac{39}{10}×\frac{2}{100}=\frac{78}{1000}=0.078$
5. $0.24×0.09=\frac{24}{100}×\frac{9}{100}=\frac{216}{10000}=0.0216$