一、口算。
$5 - 0.5 =$
$2.4 × 2 =$
$57 + 19 =$
$15.5 ÷ 5 =$
$200 - 55 =$
$16 × 40 =$
$3.5 + 4.7 =$
$840 ÷ 12 =$
$5 ÷ 25 =$
$3.02 × 10 =$
$4 × 403 =$
$9.03 - 0.43 =$
$75 ÷ 1000 =$
$7.5 + 1.05 =$
$480 ÷ 80 =$
$9.5 × 5 =$
$6.5 ÷ 100 =$
$0.5 × 300 =$
$5.48 + 4.05 =$
$0.105 × 100 =$
$36.5 ÷ 365 =$
$42 ÷ 5 =$
$4.1 - 0.41 =$
$1.04 × 3 =$
$0.25 × 40 =$
$0.83 ÷ 2 =$
$1.44 ÷ 12 =$
$32.9 ÷ 7 =$
$0.4 × 16 =$
$0.03 × 42 =$

1. 4.5
2. 4.8
3. 76
4. 3.1
5. 145
6. 640
7. 8.2
8. 70
9. 0.2
10. 30.2
11. 1612
12. 8.6
13. 0.075
14. 8.55
15. 6
16. 47.5
17. 0.065
18. 150
19. 9.53
20. 10.5
21. 0.1
22. 8.4
23. 3.69
24. 3.12
25. 10
26. 0.415
27. 0.12
28. 4.7
29. 6.4
30. 1.26

二、连一连。