题目内容

下面各题,怎样简便就怎样算.
39÷7+31×
1
7

0.625×36+
3
8
×36-36
4
9
÷[(
5
6
-
1
2
)+(
5
9
-
5
18
)]
2008
2009
×2008-2007
1
2
+
1
6
+
1
12
+
1
20
+
1
30
+
1
42
+
1
56
+
1
72
2
9
+
5
27
)×27×9.
(1)39÷7+31×
1
7

=(39+31)×
1
7

=70×
1
7

=10;

(2)0.625×36+
3
8
×36-36,
=(0.625+0.375-1)×36,
=0×36,
=0;

(3)
4
9
÷[(
5
6
-
1
2
)+(
5
9
-
5
18
)],
=
4
9
÷[
1
3
+
5
18
],
=
4
9
÷
11
18

=
8
11


(4)
2008
2009
×2008-2007,
=
2008
2009
×2009-
2008
2009
×1-2007,
=2008-
2008
2009
-2007,
=1-
2008
2009

=
1
2009


(5)
1
2
+
1
6
+
1
12
+
1
20
+
1
30
+
1
42
+
1
56
+
1
72

=1-
1
2
+
1
2
-
1
3
+
1
3
-
1
4
+
1
4
-
1
5
+
1
5
-
1
6
+
1
6
-
1
7
+
1
7
-
1
8
+
1
8
+
1
8
-
1
9

=1-
1
9

=
8
9


(6)(
2
9
+
5
27
)×27×9,
=
2
9
×72×9+
5
27
×27×9,
=144+45,
=189.
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