问题 解答题
2
9
×
3
20
×9
27×(
8
9
-
2
3
5
6
×
6
7
×
7
8
×
8
9
1
2
×
1
15
+
1
3
×
1
2
1
3
×
5
12
+
1
3
×
1
4
5
9
×21-
2
9
×21
12
5
×(
5
6
+
5
4
)×
24
25
3
4
-
5
8
×
4
5
(24+12)×
1
12
1
4
×5+
1
4
×3+
1
4
×2.
答案

(1)

2
9
×
3
20
×9,

=

2
9
×9×
3
20

=2×

3
20

=

3
10

(2)27×(

8
9
-
2
3
),

=27×

8
9
-27×
2
3

=24-18,

=6;

(3)

5
6
×
6
7
×
7
8
×
8
9

=(

5
6
×
6
7
)×(
7
8
×
8
9
),

=

5
7
×
7
9

=

5
9

(4)

1
2
×
1
15
+
1
3
×
1
2

=

1
2
×(
1
15
+
1
3
),

=

1
2
×
2
5

=

1
5

(5)

1
3
×
5
12
+
1
3
×
1
4

=

1
3
×(
5
12
+
1
4
),

=

1
3
×
2
3

=

2
9

(6)

5
9
×21-
2
9
×21,

=(

5
9
-
2
9
)×21,

=

1
3
×21,

=7;

(7)

12
5
×(
5
6
+
5
4
)×
24
25

=

12
5
×
5
6
×
24
25
+
12
5
×
5
4
×
24
25

=

48
25
+
72
25

=

24
5

(8)

3
4
-
5
8
×
4
5

=

3
4
-
1
2

=

1
4

(9)(24+12)×

1
12

=24×

1
12
+12×
1
12

=2+1,

=3;

(10)

1
4
×5+
1
4
×3+
1
4
×2,

=

1
4
×(5+3+2),

=

1
4
×10,

=

5
2

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