Since the sole reason that he does so incredibly much is that there's actually 14 of him, and they're all just called 'Black Six' instead of 'Black One through Fourteen' for the sake of the unified brand, this gives us a whole new lot of possibilities.
A simple one: Black [any number] divided by Black Zero. Since the 'Black' is present in both parts of the division, it can be omitted, so you get [any number]/0 AKA Black Infinite. Or a black hole, if your calculator doesn't support that.
And now for something more interesting: it can be used to calculate B6's parents. His parents were both equal to the root of Black Six, since √(Black Six) * √(Black Six) = Black Six.
Science-shipping. It's real.
Also, if you apply B6-mathematics to physics, you get stuff that's in the 4th Dimensioneer.