(共31张PPT)
两位数减两位数的口算
45-20 =
67-30 =
25
37
45- 3 =
67- 8 =
42
59
五十几个
二十几个
小灰兔比小白兔多摘多少个?
5□-2□
研究问题:
5□-2□
想:
5□-20=3□
3□-□=□□
拔萝卜
第一关
57-30 =
27- 2 =
57-32 =
76-60 =
16- 8 =
40-23 =
76-68 = 8
27
25
25
16
8
40-20 = 20
20- 3 = 17
17
3
30
2
2
摘蘑菇
第二关
93-57 =
93-53 =
75-29 =
75-23 =
50-27 =
50-24 =
40
36
52
46
26
23
3
5
4
4
2
2
93-57 =
93-53 =
幸运抽题
第三关
53-16
67-35
37-35
94-38
23-12
89-45
30-24
62-36
44-18
35-28
88-28
67-35
94-38
80-45
34-18
42-23
84-16
51-26
77-68 54-16
77-35
47-35
84-38
23-12
99-45
70-24
62-36
34-18
55-28
68-28
47-35 53-16
67-35
37-35
94-38
23-12
89-45
30-24
62-36
44-18
35-28
88-28
67-35
94-38
80-45
34-18
42-23
84-16
51-26
77-68 54-16
77-35
47-35
84-38
23-12
99-45
70-24
62-36
34-18
55-28
68-28
47-35
54-38
60-45
34-18
42-23
84-16
79-22
67-35
53-16
67-35
37-35
94-38
23-12
89-45
30-24
62-36
44-18
35-28
88-28
67-35
94-38
80-45
34-18
42-23
84-16
51-26
77-68 54-16
77-35
47-35
84-38
23-12
99-45
70-24
62-36
34-18
55-28
68-28
47-35 53-16
67-35
37-35
94-38
23-12
89-45
30-24
62-36
44-18
35-28
88-28
67-35
94-38
80-45
34-18
42-23
84-16
51-26
77-68 54-16
77-35
47-35
84-38
23-12
99-45
70-24
62-36
34-18
55-28
68-28
47-35
54-38
60-45
34-18
42-23
84-16
79-22
-35
64-38
53-16
67-35
37-35
94-38
23-12
89-45
30-24
62-36
44-18
35-28
88-28
67-35
94-38
80-45
34-18
42-23
84-16
51-26
77-68 54-16
77-35
47-35
84-38
23-12
99-45
70-24
62-36
34-18
55-28
68-28
47-35 53-16
67-35
37-35
94-38
23-12
89-45
30-24
62-36
44-18
35-28
88-28
67-35
94-38
80-45
34-18
42-23
84-16
51-26
77-68 54-16
77-35
47-35
84-38
23-12
99-45
70-24
62-36
34-18
55-28
68-28
47-35
54-38
60-45
34-18
42-23
84-16
79-22
89-16
53-16
67-35
37-35
94-38
23-12
89-45
30-24
62-36
44-18
35-28
88-28
67-35
94-38
80-45
34-18
42-23
84-16
51-26
77-68 54-16
77-35
47-35
84-38
23-12
99-45
70-24
62-36
34-18
55-28
68-28
47-35 53-16
67-35
37-35
94-38
23-12
89-45
30-24
62-36
44-18
35-28
88-28
67-35
94-38
80-45
34-18
42-23
84-16
51-26
77-68 54-16
77-35
47-35
84-38
23-12
99-45
70-24
62-36
34-18
55-28
68-28
47-35
54-38
60-45
34-18
42-23
84-16
79-22
67-35
70-35
53-16
67-35
37-35
94-38
23-12
89-45
30-24
62-36
44-18
35-28
88-28
67-35
94-38
80-45
34-18
42-23
84-16
51-26
77-68 54-16
77-35
47-35
84-38
23-12
99-45
70-24
62-36
34-18
55-28
68-28
47-35 53-16
67-35
37-35
94-38
23-12
89-45
30-24
62-36
44-18
35-28
88-28
67-35
94-38
80-45
34-18
42-23
84-16
51-26
77-68 54-16
77-35
47-35
84-38
23-12
99-45
70-24
62-36
34-18
55-28
68-28
47-35
54-38
60-45
34-18
42-23
84-16
79-22
72-19
口算擂台
第四关
只写得数
54-12
50-26
48-19
73-45
只写得数
42
24
29
28
54-12
50-26
48-19
73-45
设计密码
第五关
□□-□□=4□
凭密码入场:
73-31
是四十多吗?
通过
不通过
73-28
是四十多吗?
通过
不通过
53-2□
是四十多吗?
通过
不通过
72-2□
是四十多吗?
3
通过
不通过
1
通过
通过
通过
通过
通过
森林运动会
谢
谢
指
导
5□ - 2□
20
□
3□