The pth base ten repunit and the qth base ten repunit are respectively denoted by R(p) and R(q), where each of p and q exceeds 10.
Prove that R(p)*R(q) can never be equal to a palindrome.
(In reply to
Not very formal, but ... (spoiler) by Steve Herman)
I had thought of that line of reasoning, but wondered whether at some point it might be possible that, while the carries might propagate leftward, in some instance it might merely move the point of symmetry to the left and regain palindromic status, though not of the original, simple type.

Posted by Charlie
on 20091001 11:24:25 