what exactly are the numbers on the outer edge of the wilton cake divider wheel????inches?????

They are indications of where to mark your cake to separate it into equal sections. For example, if you had a 12 inch round and you wanted to do some string work, you would mark on your cake all of the lines that have a 12 next to them. This takes the guess work out of having to section your cake yourself. I hope this makes sense its easier to explain if you have a wheel and can point to the lines with the corresponding cake diameters.