一、口算。
$y - 0.3y =$
$34×60 =$
$4.5×20 =$
$2.48÷8 =$
$245 + 545 =$
$4.3x + 7x =$
$2.15×4 =$
$0.48÷3 =$
$200 - 187 =$
$5.62 - 2.42 =$
$0.324×2 =$
$570÷19 =$
$905÷5 =$
$2.51 - 1.2 =$
$0.004×8 =$
$0.36 + 5.6 =$
$0.56÷28 =$
$9.6÷100 =$
$102×80 =$
$0.38 + 10.62 =$
$0.42×1000 =$
$3.08÷4 =$
$0.2×43 =$
$432×5 =$
$0.07×30 =$
$9.7÷4 =$
$x×8 + 2.1 =$
$600÷120 =$
$60÷50 =$
$7a×8 + 4 =$

1. $y - 0.3y = 0.7y$
2. $34×60 = 2040$
3. $4.5×20 = 90$
4. $2.48÷8 = 0.31$
5. $245 + 545 = 790$
6. $4.3x + 7x = 11.3x$
7. $2.15×4 = 8.6$
8. $0.48÷3 = 0.16$
9. $200 - 187 = 13$
10. $5.62 - 2.42 = 3.2$
11. $0.324×2 = 0.648$
12. $570÷19 = 30$
13. $905÷5 = 181$
14. $2.51 - 1.2 = 1.31$
15. $0.004×8 = 0.032$
16. $0.36 + 5.6 = 5.96$
17. $0.56÷28 = 0.02$
18. $9.6÷100 = 0.096$
19. $102×80 = 8160$
20. $0.38 + 10.62 = 11$
21. $0.42×1000 = 420$
22. $3.08÷4 = 0.77$
23. $0.2×43 = 8.6$
24. $432×5 = 2160$
25. $0.07×30 = 2.1$
26. $9.7÷4 = 2.425$
27. $x×8 + 2.1 = 8x+2.1$
28. $600÷120 = 5$
29. $60÷50 = 1.2$
30. $7a×8 + 4 = 56a+4$

二、将下面各数分别填入相应的框里。
35
76
51
27
62
405
300
74
108
471

既是2的倍数，
又是3的倍数
既是3的倍数，
又是5的倍数
同时是
2,3,5的倍数

1. 既是2的倍数，又是3的倍数：300,108
2. 既是3的倍数，又是5的倍数：405,300
3. 同时是2,3,5的倍数：300