1-56+712-920+1130-1342+1556-1772+1990=______.-数学

题目简介

1-56+712-920+1130-1342+1556-1772+1990=______.-数学

题目详情

1-
5
6
+
7
12
-
9
20
+
11
30
-
13
42
+
15
56
-
17
72
+
19
90
=______.
题型:解答题难度:中档来源:不详

答案

1-class="stub"5
6
+class="stub"7
12
-class="stub"9
20
+class="stub"11
30
-class="stub"13
42
+class="stub"15
56
-class="stub"17
72
+class="stub"19
90

=1-(class="stub"1
2
+class="stub"1
3
)+(class="stub"1
3
+class="stub"1
4
)-(class="stub"1
4
+class="stub"1
5
)+(class="stub"1
5
+class="stub"1
6
)+(class="stub"1
6
+class="stub"1
7
)-(class="stub"1
7
+class="stub"1
8
)+(class="stub"1
8
+class="stub"1
9
)-(class="stub"1
9
-class="stub"1
10
),
=1-class="stub"1
2
+class="stub"1
10

=class="stub"1
2
+class="stub"1
10

=class="stub"3
5

故答案为:class="stub"3
5

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