On a blackboard there are
numbers. In each step we select two numbers from the blackboard and replace both of them by their sum. Determine all numbers
for which it is possible to yield
identical number after a finite number of steps.
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On a blackboard there are $n \geq 2, n \in \mathbb{Z}^{+}$ numbers. In each step we select two numbers from the blackboard and replace both of them by their sum. Determine all numbers $n$ for which it is possible to yield $n$ identical number after a finite number of steps.
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