问题 解答题
(1)
2
3
+
3
5

(2)1
1
3
-
7
12
+
9
20
-
11
30
+
13
42
-
15
56

(3)36.785-(29-3.215)
(4)2009÷2009
2009
2010
+
1
2011
答案

(1)

2
3
+
3
5

=

10
15
+
9
15

=

19
15

=1

4
15

(2)1

1
3
-
7
12
+
9
20
-
11
30
+
13
42
-
15
56

=(

4
3
+
9
20
+
13
42
)-(
7
12
+
11
30
+
15
56
),

=(

560
420
+
189
420
+
130
420
)-(
490
840
+
308
840
+
225
840
),

=

879
420
-
1023
840

=

1758
840
-
1023
840

=

735
840

=

7
8

(3)(3)36.785-(29-3.215),

=36.785+3.215-29,

=40-29,

=11;

(4)2009÷2009

2009
2010
+
1
2011

=2009÷

2009×2010+2009
2010
+
1
2011

=2009÷

2009×2011
2010
+
1
2011

=2009×

2010
2009×2011
+
1
2011

=

2010
2011
+
1
2011

=1.

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