问题 解答题
脱式计算.(能简算的要简算)
2
5
×
1
4
+
1
4
×
3
5

5
11
+
7
44
)×88
5
8
×
12
31
×
8
5

4
5
×
6
7
×15×21.
答案

(1)

2
5
×
1
4
+
1
4
×
3
5

=(

2
5
+
3
5
)×
1
4

=1×

1
4

=

1
4

(2)(

5
11
+
7
44
)×88

=

5
11
×88+
7
44
×88

=40+14

=54;

(3)

5
8
×
12
31
×
8
5

=(

5
8
×
8
5
)×
12
31

=1×

12
31

=

12
31

(4)

4
5
×
6
7
×15×21

=(

4
5
×15)×(
6
7
×21)

=12×18

=216.

改错题
单项选择题