问题 解答题
脱式计算.(能简算的要简算)
21×
5
14
×
7
5
30×(
2
5
+
1
6
-
4
15
);
24×
3
8
+56÷
8
3
0.25×32×12.5;
3
25
÷
1
10
+
1
5
8
9
×[
3
4
-(
7
16
-
1
4
)]
答案

(1)21×

5
14
×
7
5

=21×(

5
14
×
7
5

=21×

1
2

=

21
2

(2)30×(

2
5
+
1
6
-
4
15

=30×

2
5
+30×
1
6
-30×
4
15

=12+5-8

=9

(3)24×

3
8
+56÷
8
3

=24×

3
8
+56×
3
8

=(24+56)×

3
8

=80×

3
8

=30

(4)0.25×32×12.5

=0.25×4×8×12.5

=(0.25×4)×(8×12.5)

=1×100

=100

(5)

3
25
÷
1
10
+
1
5

=

3
25
×10+
1
5

=

6
5
+
1
5

=

7
5

(6)

8
9
×[
3
4
-(
7
16
-
1
4
)]

=

8
9
×[
3
4
+
1
4
-
7
16
]

=

8
9
×[1-
7
16
]

=

8
9
×
9
16

=

1
2

解答题
单项选择题