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jmc

number theory junior

Problem

(A)
(B)
(C)
(D)
Solution
Put the numbers in groups of : The first group has a sum of . The second group increases the two positive numbers on the end by , and decreases the two negative numbers in the middle by . Thus, the second group also has a sum of . Continuing the pattern, every group has a sum of , and thus the entire sum is , giving an answer of .
Final answer
C