题目内容
下面各题,怎样简便就怎样算. 39÷7+31×
| 0.625×36+
| ||||||||||||||||||||
|
| ||||||||||||||||||||
| (
|
(1)39÷7+31×
,
=(39+31)×
,
=70×
,
=10;
(2)0.625×36+
×36-36,
=(0.625+0.375-1)×36,
=0×36,
=0;
(3)
÷[(
-
)+(
-
)],
=
÷[
+
],
=
÷
,
=
;
(4)
×2008-2007,
=
×2009-
×1-2007,
=2008-
-2007,
=1-
,
=
;
(5)
+
+
+
+
+
+
+
,
=1-
+
-
+
-
+
-
+
-
+
-
+
-
+
+
-
,
=1-
,
=
;
(6)(
+
)×27×9,
=
×72×9+
×27×9,
=144+45,
=189.
1 |
7 |
=(39+31)×
1 |
7 |
=70×
1 |
7 |
=10;
(2)0.625×36+
3 |
8 |
=(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 |
2009 |
2008 |
2009 |
=2008-
2008 |
2009 |
=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 |
=
2 |
9 |
5 |
27 |
=144+45,
=189.
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