内容正文:
分数乘整数
2
9
2
9
9
9
+
=
2+2
=
4
2
2
2
2+2+2
6
9
9
9
+
+
=
=
9
9
×
7
3
35
5
1
a
×
( )
( )
a
×
分数乘整数,就是求
……
几分之几相加的和是多少
几个
1.尝试计算,注意写出计算过程。
2.完成后小组内交流计算方法,
看谁讲的最清楚、最明白。
探究要求:
×
4
=
2
9
2
9
2
9
2
9
2
9
+
+
+
=
+
+
+
2
9
2
2
2
=
×
2
9
4
=
8
9
×
3
=
3
7
3
7
3
7
3
7
+
+
=
+
+
3
7
3
3
=
×
3
7
3
=
9
7
×
5
=
1
2
+
+
+
+
=
1
2
1
2
1
2
1
2
1
2
+
+
+
+
1
1
1
1
=
2
1
1
=
×
5
2
5
2
×
4
=
2
9
2
9
2
9
2
9
2
9
+
+
+
=
+
+
+
2
9
2
2
2
=
×
2
9
4
=
8
9
×
3
=
3
7
3
7
3
7
3
7
+
+
=
+
+
3
7
3
3
=
×
3
7
3
=
9
7
×
5
=
1
2
+
+
+
+
=
1
2
1
2
1
2
1
2
1
2
+
+
+
+
1
1
1
1
=
2
1
1
=
×
5
2
5
2
分子
……
分母
……
与整数相乘
不变
2
7
×
3
=
6
7
7
5
12
11
77
15
小试牛刀
2×3
7
=
1
5
×
7
=
3
11
×
4
=
11
15
×
7
=
3×4
11
=
1×7
5
=
11×7
15
=
3
14
×
35
=
7
30
×
2
=
19
20
×
5
=
2
13
×
26
=
大显身手
火眼金睛
1
5
×
7
=
1
35
(1)
1
4
×
9
=
(2)
×
4
=
23
12
(3)
×
( )
( )
( )
×
×
7
5
9
4
48
23
36
4
9
1
4
1
=
3
23
12
=
×
4
1
3
23
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