Computing the nth digit of pi
It is really quite remarkable that we can compute the nth digit of pi without first computing the other n-1 digits!
http://www.plouffe.fr/simon/articles/Miraculous.pdf Links to an external site.
https://www.math.hmc.edu/funfacts/ffiles/20010.5.shtml Links to an external site.
https://www.carma.newcastle.edu.au/jon/bbp-bluegene.pdf Links to an external site.
http://www.lacim.uqam.ca/~plouffe/Simon/articlepi.html Links to an external site.