c = 2πr,then
π = c/2rπ simply by dividing length of the long side (22”) by the length of the short side (6.5”). The result they got (3.338...) is only about 8% off – not bad at all for a kitchen-table experiment!
Now that you've computed π from first principles, you can celebrate by eating the pizza!
I told Clay that he needs to continue his pizza experiments to see if they can refine the value of π just a bit more...