一、口算。
$7.9 - 5 =$
$3.4 ÷ 2 =$
$41 × 5 =$
$3 ÷ 15 =$
$100 - 36 =$
$2.08 ÷ 10 =$
$0.2 × 60 =$
$0.5 + 1.3 =$
$45 + 155 =$
$180 ÷ 90 =$
$0.12 × 7 =$
$4.2 ÷ 21 =$
$4.2 × 8 =$
$14.7 ÷ 7 =$
$0.04 × 200 =$
$3.07 - 0.73 =$
$0.45 × 40 =$
$464 ÷ 8 =$
$4.32 ÷ 8 =$
$1.08 + 3.1 =$
$0.405 × 100 =$
$6.4 - 0.44 =$
$1.35 × 3 =$
$5.8 ÷ 58 =$
$1.06 × 7 =$
$4.57 + 6.43 =$
$48 × 200 =$
$16.2 ÷ 4 =$
$80 ÷ 25 =$
$0.25 × 16 =$

1. 2.9
2. 1.7
3. 205
4. 0.2
5. 64
6. 0.208
7. 12
8. 1.8
9. 200
10. 2
11. 0.84
12. 0.2
13. 33.6
14. 2.1
15. 8
16. 2.34
17. 18
18. 58
19. 0.54
20. 4.18
21. 40.5
22. 5.96
23. 4.05
24. 0.1
25. 7.42
26. 11
27. 9600
28. 4.05
29. 3.2
30. 4

二、在下面的框里填合适的数。

14的因数：1,2,7,14
22的因数：1,2,11,22
36的因数：1,2,3,4,6,9,12,18,36
48的因数：1,2,3,4,6,8,12,16,24,48