Uhhh, Cybertech.... how do you count to 10? With 1 hand?
The usually teach circumference first.
Pi as a half-circle, once you start using graphs and trig makes a whole lot of sense.
I've read there's been recent discovery of a pile of Archimedes' writings. The man was on to the limit or working on it before the Roman soldier showed him who's boss.
There's an ancient Arabic proof of the Pythagorean Theorem from centuries before Pythagoras that I always liked because it's geometric. But my hat's off to the Indian scholars who invented zero and went on to other depths (finite series, maybe infinite series) maybe 1000 years before Newton.
I remember finding out why the volume of a sphere is 4/3 Pi R^3, why the 4/3. It doesn't "prove" anything but the volume of a sphere but it was nice to know how. Which brings me to this whole "proves" thing. Some people have awfully loose ideas about what proof is, ie: "I want" + "something convenient with no real connection" = "proof". Please.. just.. think.