Great point about #comparing #floating #point #numbers https://davidamos.dev/the-right-way-to-c.. The main take-away is to make the #comparison to some #significantfigures rather than doing a direct comparison.
Very cool #hack to use #regex to #test whether a #number is #prime or not: https://www.noulakaz.net/2007/03/18/a-re.. As I understand it, it #tests the #numbers of #ones in the #string.