The wheel will assist you in figuring the cost per ounce in a package, as long as $3 is the highest price you will be asked to pay.
This wheel is 5.25 by 3.25 inches. The copyright date is 1961 and is in reasonably good shape -- just like me! It was provided by the good folks at The Jarrell Company in Dallas. They're still around, but I'm sure they aren't handing out anything as good as a knowledge wheel.