问题 解答题
用简便方法计算.
5
4
×
1
2
×
3
5
3
7
×
1
5
×
7
9
18×
2
3
×
5
6
 
20
51
×
17
30
×9
11
36
×27×
4
33
1
5
6
×
2
3
×
3
22
答案

(1)

5
4
×
1
2
×
3
5

=

5
4
×
3
5
×
1
2

=

3
4
×
1
2

=

3
8

(2)

3
7
×
1
5
×
7
9

=

3
7
×
7
9
×
1
5

=

1
3
×
1
5

=

1
15

(3)18×

2
3
×
5
6

=12×

5
6

=10;

(4)

20
51
×
17
30
×9,

=

2
9
×9,

=2;

(5)

11
36
×27×
4
33

=

11
36
×
4
33
×27,

=

1
27
×27,

=1;

(6)1

5
6
×
2
3
×
3
22

=

11
6
×
3
22
×
2
3

=

1
4
×
2
3

=

1
6

单项选择题
单项选择题