[Guest]

Each of X any Y is a tridecimal (base 13) positive integer, where X is formed by writing the digit 4 precisely 666 times and, Y is formed by writing the digit 6 precisely 666 times.

Determine the distinct digits that appear in the tridecimal representation of the product X*Y.

**** For an extra challenge, solve this problem using only pencil/pen and paper.

[superprismatic]

from high order digit to low order:

six hundred sixty-four 1s, one 0, six hundred sixty-five As, and one B