一、口算。
45 + 45 =
0.9 × 4 =
13.8 - 2.9 =
7.2 ÷ 6 =
135 - 60 =
13 × 20 =
5.4 × 3 =
0.93 ÷ 3 =
805 ÷ 5 =
6.2 × 2 =
0.125 × 100 =
0.78 + 22.2 =
77.7 ÷ 7 =
9.6 ÷ 12 =
0.09 × 110 =
2.91 + 9.9 =
150 × 60 =
3.88 - 1.9 =
0.433 ÷ 10 =
0.6 - 0.24 =
2400 ÷ 120 =
1.25 × 200 =
4.24 ÷ 8 =
0.43 × 50 =
0.52 + 0.48 =
0.3 × 130 =
1.5 ÷ 75 =
0.07 × 20 =
4.78 ÷ 2 =
10 ÷ 25 =

1. 90
2. 3.6
3. 10.9
4. 1.2
5. 75
6. 260
7. 16.2
8. 0.31
9. 161
10. 12.4
11. 12.5
12. 22.98
13. 11.1
14. 0.8
15. 9.9
16. 12.81
17. 9000
18. 1.98
19. 0.0433
20. 0.36
21. 20
22. 250
23. 0.53
24. 21.5
25. 1
26. 39
27. 0.02
28. 1.4
29. 2.39
30. 0.4

二、将下面各数分别填入相应的框里。
1 45 43 56 71 63 84 85
13 15 30 49 2 73 91 98

奇数：1,45,43,71,63,85,13,15,49,73,91
偶数：56,84,30,2,98
质数：43,71,13,2,73
合数：45,56,63,84,85,15,30,49,91,98