Correction: 5:40 It was the Chudnovsky brothers. Correction: 5:48 The expression is incorrect. The expression is not infinite and the first two should also be in a radical. the actual expression is 768 sqrt(2 - (sqrt(2 + (sqrt(2 + (sqrt(2 + (sqrt(2 + (sqrt(2 + (sqrt(2 + (sqrt(2 + (sqrt(2 + 1)))))))))))))))) = ... It doesn't exactly equal pi. You can find it at the link below under "development of efficient formulae." %CF%80 My apologies for the confusion. In this video, I rank the most famous approximations of pi in a tier list, from ones as simple as 22/7, to more complex approximations like continued fractions and the summations developed by Rumanujan. Some of these are surprisingly accurate or converge to pi rather quickly. Others? Not so much. I ranked based on a combination of precision, interesting structure, and historical significance. What’s your favorite pi approximation? Let me know in the comments.