Ah! That's more nuanced. Sadly I do not speak Japanese so I didn't read the original source. > I wonder how far I could have gotten with it if, at the age of

Ah! That's more nuanced. Sadly I do not speak Japanese so I didn't read the original source. > I wonder how far I could have gotten with it if, at the age of 18 or 19, I had encountered it on an exam and had just twenty or thirty minutes to try to come up with a proof. It's a nice one. Especially because since pi shows up in so many places there are multiple ways of doing it.