ZimmieFun pi fact which too few people know: the digits actually do follow a pattern! In 1995, Simon Plouffe discovered a formula for pi which he used to create what is called a “spigot algorithm”. This algorithm allows a given digit of pi to be calculated *without* calculating the preceding digits. Originally, it only worked in hexadecimal, but he later discovered another algorithm for a given digit of pi in decimal.
The known spigot algorithms for pi are non-constant time. Calculating the millionth digit takes longer than the thousandth. Still, they’re interesting because they have much lower memory requirements than other methods of calculating a value for pi.