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{
\bf Attendance Quiz \# 18 for Dr. Z.'s Number Theory
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{\bf NAME:} (print!) $\underline
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{\bf E-MAIL ADDRESS:} (print!) 
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{\bf 1.} Which of the following  are perfect numbers? Explain!

 {\bf a.} $49$ ; {\bf b.} $28$ 

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{\bf 2.} (Without peeking at your notes), prove that if $p$ is a prime, and $2^p-1$ is also a prime, then
$$
2^{p-1} \cdot (2^p -1) \quad 
$$
is a perfect number.


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