# What does it mean to cross a scalar with a vector in a 2D plane?

At the moment, I'm following this page to create a physics engine.

As per that page, I need to cross angular velocity by a distance vector to get relative torque and such, but I'm not sure how (in a 2D plane), you can cross a scalar(angular velocity), and a vector(such as the distance vector). I've assumed so far that you multiply the magnitude, but obviously this isn't correct, as I continue the debugging of my flimsy code. What am I missing?