﻿ National Pi Day

# National Pi Day

 Yesterday was 3/14 (in American data notation), which is National Pi Day.* Why March 14th? Well, to two decimal places, Pi is 3.14 *It's also Albert Eintsein's Birthday.

### Trivia

Pi is an irrational number. In decimal notation it goes on forever. If you search hard enough, and deep enough, you can find pretty much anything in the patterns of its digits (your telephone number, social security number, famous dates in history …). To show how you can find pretty much anything, I even wrote a posting about how you can find a bitmap of Pi inside itself.

Last year I searched pi looking for the last occuring distinct combination of four digits in the article Pi, PINs and Permutations. (The answer is 6176).

You can even estimate Pi by throwing a piece of bent wire onto a wooden floor.

### Ordinal and Cardinal

The 1st decimal digit of Pi, is also the number '1'. These are the same.

However, the 2nd decimal digit of Pi is a '4'. This is not a match.

What is the next time that the nth digit corresponds to the decimal string? This next happens at position 16,470.

• At the 16,470th digit of Pi, the numbers …16470… occur.

• At the 44,899th digit of Pi, the numbers …44899… occur.

• At the 79,873,884th digit of Pi, the numbers …79873884 … occur.

• At the 711,939,213th digit of Pi, the numbers …711939213… occur.

(I stopped searching at this point).