\(P\) and \(Q\) are prime numbers less than \(70.\) What is the units digit of \(P\cdot Q?\)

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\(P\) and \(Q\) are prime numbers less than \(70.\) What is the units digit of \(P\cdot Q?\)

(1) Units’ digit of \(P^{4k+2}-Q\) is equal to \(7,\) where \(k\) is a positive integer.

(2) Units digit of the expression \(PQ+Q\cdot (Q+1)-Q^2\) is a perfect cube.

Answer: E

Source: e-GMAT
Source: — Data Sufficiency |