Prove that an integer with digits '1' is not a perfect square.

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If you work out p(mod 12) for p a prime, what are the possibilities? Excepting 2 and 3. What does this imply for p^2(mod 12)?

Dick Recognitions: Homework Help Science Advisor	If you work out p(mod 12) for p a prime, what are the possibilities? Excepting 2 and 3. What does this imply for p^2(mod 12)?