Almost 12345654321
Number Theory
Level
3
Is \( {\color{pink}1}{\color{grey}{2}}{\color{green}{3}}{\color{blue}{4}}{\color{red}555}{\color{blue}{4}}{\color{green}{3}}{\color{grey}{2}}{\color{pink}1} \) prime?
Hint: You may use the fact that \( 111111 \times 111111 = {\color{pink}1}{\color{grey}{2}}{\color{green}{3}}{\color{blue}{4}}{\color{red}5}6{\color{red}5}{\color{blue}{4}}{\color{green}{3}}{\color{grey}{2}}{\color{pink}1} \). This is similar to, but not identical to the above number, due to the middle \( 6 \).
by
Chung Kevin