Today is Pi day: the month, the third of the year, followed the date, the fourteenth, make up the first three digits of the key mathematical constant.The UK's Guardian tracks down some numerologists, for whom today is important, but forgets the most famous Pi obsessives of all, Google's founders, who determined the number of shares to sell in the search engine's initial public offering by taking Pi from first to eight decimal point. When Google is powerful enough to warrant a public holiday, 3.14 will be the day.