\textbf{37.} By placing the digit 3 between two digits of the three-digit number $(a \circ a)$, a new number $a$ is formed. What is the maximum number of values that $a$ can take?
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(1) zero \hspace{1cm} (2) $1$ \hspace{1cm} (3) $2$ \hspace{1cm} (4) $3$
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