How printf works : https://web.archive.org/web/20160417011548/http://alain.dancel.free.fr/c/c60_10.htm
https://www.ibisc.univ-evry.fr/~petit/Enseignement/Modelisation-en-C/printf-conversions-format.pdf
Understand floats http://www.ryanjuckett.com/programming/printing-floating-point-numbers/part-2/ https://en.wikipedia.org/wiki/IEEE_754-1985 https://en.wikipedia.org/wiki/Extended_precision https://www.youtube.com/watch?v=8afbTaA-gOQ