一、口算。
$82 - 28 =$
$74 × 2 =$
$790 + 210 =$
$28 × 3 =$
$85 ÷ 5 =$
$130 - 13 =$
$70 - 18 =$
$18 × 4 =$
$640 ÷ 2 =$
$57 ÷ 3 =$
$68 + 17 =$
$153 + 227 =$
$3 × 17 =$
$65 ÷ 5 =$
$800 × 8 =$
$600 ÷ 6 =$
$42 ÷ 3 =$
$720 × 3 =$
$75 × 4 =$
$100 - 39 =$
$520 ÷ 4 =$
$100 + 43 =$
$106 × 6 =$
$920 ÷ 4 =$

1. 82 - 28 = 54
2. 74 × 2 = 148
3. 790 + 210 = 1000
4. 28 × 3 = 84
5. 85 ÷ 5 = 17
6. 130 - 13 = 117
7. 70 - 18 = 52
8. 18 × 4 = 72
9. 640 ÷ 2 = 320
10. 57 ÷ 3 = 19
11. 68 + 17 = 85
12. 153 + 227 = 380
13. 3 × 17 = 51
14. 65 ÷ 5 = 13
15. 800 × 8 = 6400
16. 600 ÷ 6 = 100
17. 42 ÷ 3 = 14
18. 720 × 3 = 2160
19. 75 × 4 = 300
20. 100 - 39 = 61
21. 520 ÷ 4 = 130
22. 100 + 43 = 143
23. 106 × 6 = 636
24. 920 ÷ 4 = 230

二、计算下面各题。
$68÷ 4+783$
$360÷ (11-8)$
$(540+90)÷ 5$
$255× (27÷ 9)$
$392÷ (21÷ 3)$
$9× (105+66)$

1. $68÷ 4+783$ = 800
2. $360÷ (11-8)$ = 120
3. $(540+90)÷ 5$ = 126
4. $255× (27÷ 9)$ = 765
5. $392÷ (21÷ 3)$ = 56
6. $9× (105+66)$ = 1539