Last nonzero digit coloring
= Last nonzero digit coloring
For a <prime number> $p$, write a positive integer as $x=p^{v_p(x)}u$ with $p\nmid u$. Its last nonzero base-$p$ digit is $u\bmod p$, an element of $\{1,\ldots,p-1\}$. Assigning this digit as the color gives the last nonzero digit coloring used in the necessity proof of <Rado's theorem>.