问题 解答题
怎样简便怎样算.
5
12
×
7
25
×
3
14
5
6
×
1
4
+
5
6
×
3
4
3
86
×85
答案

(1)

5
12
×
7
25
×
3
14

=

7
60
×
3
14

=

1
40

(2)

5
6
×
1
4
+
5
6
×
3
4

=(

1
4
+
3
4
)×
5
6

=1×

5
6

=

5
6

(3)

3
86
×85,

=

3
86
×(86-1),

=

3
86
×86-
3
86
×
1,

=3-

3
86

=2

83
86

判断题
判断题