The formula is as followed:

Kentucky crap shoot divided by Northern Alabama pig poop times #
Tennessee virgins square rooting that number carried to the power of
what ever number is hit on the dart board that day.
Give or take a .010.
Unless of course you added winglets and now you have a glider that
automatically gets a number in the .80 range adjusted with the
formulae above.
A 1-26 with winglets is equal to a Nimbus lll.
It's not an exact science, but it goes far in keeping the masses
confuse.
R