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National and Regional Contests
USA Contests
MAA AMC
AMC 8
1990 AMC 8
16
Sum and Subtract
Sum and Subtract
Source:
June 27, 2011
Problem Statement
1990
−
1980
+
1970
−
1960
+
⋯
−
20
+
10
=
1990-1980+1970-1960+\cdots-20+10 =
1990
−
1980
+
1970
−
1960
+
⋯
−
20
+
10
=
(A)
−
990
(B)
−
10
(C)
990
(D)
1000
(E)
1990
\text{(A)}\ -990\qquad\text{(B)}\ -10\qquad\text{(C)}\ 990\qquad\text{(D)}\ 1000\qquad\text{(E)}\ 1990
(A)
−
990
(B)
−
10
(C)
990
(D)
1000
(E)
1990
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