问题 解答题
计算下面各题,能简便的尽量简便.
5
6
+
7
8
-
5
12
)÷
1
24
[
5
6
-(
5
14
-
2
7
)]×
7
18
20.07×1994-19.93×2007
2.5×0.875+0.25×1.25999
8
9
+99
8
9
+9
8
9
+
1
3
2.5-
5
12
-
1
6
÷
2
7
答案

(1)(

5
6
+
7
8
-
5
12
)÷
1
24

=(

5
6
+
7
8
-
5
12
)×24,

=

5
6
×24+
7
8
×24-
5
12
×24,

=20+21-10,

=31,

(2)[
5
6
-(
5
14
-
2
7
)]×
7
18

=[

5
6
-
1
14
7
18

=[

35
42
-
3
42
7
18

=

32
42
×
7
18

=

8
27

(3)20.07×1994-19.93×2007,

=(20.07×100)×(1994÷100)-19.93×2007,

=2007×19.94-19.93×2007,

=2007×(19.94-19.93),

=2007×0.01,

=20.07,

(4)2.5×0.875+0.25×1.25,

=2.5×0.875+(0.25×10)×(1.25÷10),

=2.5×0.875+2.5×0.125,

=2.5×(0.875+0.125),

=2.5×1,

=2.5,

(5)999

8
9
+99
8
9
+9
8
9
+
1
3

=(999+

8
9
)+(99+
8
9
)+(9+
8
9
)+
1
3

=(1000-1+100-1+10-1)+(

8
9
×3+
1
3
),

=1110-3+3,

=1110,

(6)2.5-

5
12
-
1
6
÷
2
7

=2.5-

5
12
-
1
6
×
7
2

=2.5-

5
12
-
7
12

=2.5-(

5
12
+
7
12
),

=2.5-1,

=1.5,

判断题
单项选择题