Halflife

pick an atom. will it make it?

pick one of a hundred atoms and toss: each flips its own coin, about half decay every toss, never the ones you expect

Each atom has even odds of decaying in one half-life, so a toss of a hundred coins is one half-life: nobody can say which atom goes, and keeping a survivor or switching to a fresh one makes no difference, because an atom does not age. The count is what is regular: about half are left after every toss, and the rows follow 100 x 2^-n. That is how carbon dating works: count what is left of the carbon-14 in a bone, and every halving is 5,730 years.

Concepts: radioactive-decay, probability.

An interactive you play with one thumb, on Wundr.