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Prove that a composite number $n$ has a factor $k \leq \sqrt{n}$.

Do we prove by proof by contrapositive?

Prove that a prime number $n$ has no factor $k \leq \sqrt{n}$.

Any tip?

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    The purported "contrapositive" is not really the contrapositive of the original statement. I suggest starting with the original statement. What do you know about a composite number?2012-11-29

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