问题 解答题
用简便方法计算:
5
7
×
9
8
×1
2
5
×
8
9
36×(
5
12
-
1
6
)
1
4
÷(3-
5
13
-
8
13
)
5
6
-
2
3
)
÷
10
9
答案

(1)

5
7
×
9
8
×1
2
5
×
8
9

=(

5
7
×
7
5
)×(
9
8
×
8
9
),

=1×1,

=1;

(2)36×(

5
12
-
1
6
),

=36×

5
12
-36×
1
6

=15-6,

=9.

(3)

1
4
÷(3-
5
13
-
8
13
)

=

1
4
÷[3-(
5
13
+
8
13
)],

=

1
4
÷[3-1],

=

1
4
÷2,

=

1
8

(4)(

5
6
-
2
3
10
9

=

1
6
×
9
10

=

3
20

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