MathDB
Sum divided by member

Source: St Petersburg Olympiad 2018, Grade 9, P2

July 13, 2018
number theory

Problem Statement

n>1n>1 is odd number. There are numbers n,n+1,n+2,...,2nāˆ’1n,n+1,n+2,...,2n-1 on the blackboard. Prove that we can erase one number, such that the sum of all numbers will be not divided any number on the blackboard.
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