Tonight at dinner, the 12yo wanted to know about irrational numbers. So, I got to bring up the Pythagoreans and how a god killed Hippasus for the discovery.¹ Though I'd always heard it told he was sentenced to death. ;)

¹ https://en.wikipedia.org/wiki/Hippasus

JavaScript to estimate π using my favorite method, comparing random dots that fall inside and outside of a circle:

function est_pi(dots) {
let inside = 0;
for (let i = 0; i < dots; i++) {
let x = Math.random()*2-1;
let y = Math.random()*2-1;
if (x*x + y*y <= 1) {
inside++;
}
}
return 4 * (inside/dots);
}

console.log("π ≈ "+est_pi(100000))