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Given that p is greater or equal to 7 and is a prime number, evaluate \(1^{-1} \cdot 2^{-1} + 2^{-1} \cdot 3^{-1} + 3^{-1} \cdot 4^{-1} + \cdots + (p-2)^{-1} \cdot (p-1)^{-1} \pmod{p}.\)

 Jul 18, 2019
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The answer is 2.

 Nov 8, 2019

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