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All odd digit (Posted on 2020-10-05)

Find all positive integers n such that the decimal representation of n² consists of odd digits only.

No Solution Yet Submitted by Danish Ahmed Khan

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Solution without formal proof

| Comment 1 of 7

There are only two: 1 and 3.

Tested by a computer program up to n=10,000,000

Posted by Larry on 2020-10-05 09:05:15

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