MathDB
Prime #'s

Source: 2021 Fall AMC 12A #4

November 11, 2021
AMCAMC 12AMC 12 A

Problem Statement

The six-digit number 2‾ 0‾ 2‾ 1‾ 0‾ A‾\underline{2}\,\underline{0}\,\underline{2}\,\underline{1}\,\underline{0}\,\underline{A} is prime for only one digit A.A. What is A?A?
(<spanclass=′latex−bold′>A</span>) 1(<spanclass=′latex−bold′>B</span>) 3(<spanclass=′latex−bold′>C</span>) 5(<spanclass=′latex−bold′>D</span>) 7(<spanclass=′latex−bold′>E</span>) 9(<span class='latex-bold'>A</span>)\: 1\qquad(<span class='latex-bold'>B</span>) \: 3\qquad(<span class='latex-bold'>C</span>) \: 5 \qquad(<span class='latex-bold'>D</span>) \: 7\qquad(<span class='latex-bold'>E</span>) \: 9
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