(wow those XOR GATES are a pain the asterisk!)
https://www.youtube.com/watch?v=OpLU__bhu2w#t=8m27s
I likes maths.
https://www.youtube.com/user/standupmaths/videos
...
I love this guy's youthful energy, it reminds me of Maths Smiths as The Doctor.
https://www.youtube.com/watch?v=HrRMnzANHHs#t=6m32s <<< π ...calculated by hand with prime numbers (!)
// edit: I just threw this together, confirms his hard work...
//for each of p=[1,3,5,7,9,11,13,15,17,19] add by 1/P where P is -p for 3,7,11 etc.
var p=[1,3,5,7,9,11,13,15,17,19],v=0,i=0,L=p.length,n;for(;i<L;i++){n=p[ i ],v+=1/(i%2?0-n:n)};console.log(4*v);
//over time the result is closer to PI as your primes extend well past 19... //e.g. (100)="3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97"
getPrimes=function(x){var a=[2,3],i=5;for(;i<=x;i+=2)if(a.every(function(p){return i%p})){a.push(i)}return a.slice(1)};
//Sieve of Eratosthenes (simple) = https://stackoverflow.com/questions/21966000/need-to-generate-prime-numbers-in-javascript/21966214#21966214
//Sieve of Sundaram (yikes!) = https://stackoverflow.com/questions/11966520/how-to-find-prime-numbers-between-0-100/41434702#41434702
Matt Parker talks about what makes 277777788888899 so special...
https://www.youtube.com/watch?v=Wim9WJeDTHQ
...comments argue about whether he should be upgrading to Python 3 instead of Python 2 >_<