Abstract: Coloring numbers are one of the simplest combinatorial invariants of knots
and links to describe. And with Joyce's introduction of quandles, we can
understand them more algebraically. But can we extend these invariants to
tangles -- knots and links with free ends? Indeed we can, once we categorify.
Starting from the definition of coloring numbers, we will categorify them and
establish this extension to tangles. Then, decategorifying will leave us with
matrix representations of the monoidal category of tangles.