问题 解答题
脱式计算,能简算的要简算.
2
3
÷8+
1
8
×
1
3
1
2
-
5
12
-
1
12
3
7
×(
4
5
-
2
3
)÷
2
15
19
30
×31-
19
30
答案

(1)

2
3
÷8+
1
8
×
1
3

=

2
3
×
1
8
+
1
8
×
1
3

=

1
8
×(
2
3
+
1
3
),

=

1
8
×1,

=

1
8

(2)

1
2
-
5
12
-
1
12

=

1
2
-(
5
12
+
1
12
),

=

1
2
-
1
2

=0;

(3)

3
7
×(
4
5
-
2
3
)÷
2
15

=

3
7
×
2
15
×
15
2

=

3
7

(4)

19
30
×31-
19
30

=

19
30
×(31-1),

=

19
30
×30,

=19.

单项选择题
名词解释