Friday 13th is a day of dread and fear for many especially those who suffer from Triskaidekaphobia, or the fear of 13. Strangely enough not everyone in the world thinks 13 is an unlucky number. For example, in many Asian countries 4 is the number that is the unlucky one because the Chinese word, for example, for 4 is similar to the word for death. Here are some other unlucky numbers from around the world.
So Pi-Day this weekend is not just any old Pi Day. It's Pi Day of the Century because 3.1415, the first four decimal places of Pi is also the complete date 3/14/15. This has set off great excitement in the profession of math education There are all sorts of things you can do to find out about Pi of the century. Here's some really interesting info about Pi. Here's Pi at MOMATH and here is Pi Day in Chicago. And, of course, Pi Day of the Century at the NY Times.
Something most people in the US don't realize is that Pi Day is only celebrated in the US because in the rest of the world the date is written differently.
And of course, the most important thing to remember about Pi is that it is a ratio between the circumference and the diameter of a circle. The circumference of every circle is just over 3 times the distance across the middle. If the diameter is 7 the circumference is 22.