There are lots of cool numbers out there. People have their own personal lucky numbers, and some societies have collective unlucky numbers such as 13 and 666. Here at Cool Numbers, we are currently focused on cool numbers in dollar bills. Some numbers would be obviously cool and pleasing, such as 12344321. But others are more subtle, such as 17397533.

For probability calulations, it is assumed that there is a uniform, random distribution of serial numbers between 00000000 and 99999999. We realize this may not be entirely true, and we welcome specific evidence indicating the true distribution of serial numbers

For now, there is a limited set of criteria, or rules, used in the number crunching, but suggestions are most welcome in the contact page.

In the mean time, here are some links to other interesting sources related to numbers and patterns:

Descriptions and Lists of Interesting Numbers
The Penguin Dictionary of Curious and Interesting Numbers is a very interesting book that lists all sorts of numbers that has an interesting property. What number can be expressed as the sum of each of its digits cubed? To find that answer, go to the book. Or, for those seeking instant gratification, go to this site that offers similar observations: http://www.stetson.edu/~efriedma/numbers.html. Still others will find Number Gossip to be an interesting collection of properties of numbers. In fact, Cool Numbers hopes to incorporate some of these properties into the site in the future.

Phone Numbers & Patterns
http://www.phonespell.org
Enter your phone number (with or without area code), and this website will list several possible words and phrases that your phone number spells!

Prime Numbers
http://www.utm.edu/research/primes/index.html
Learn all about prime numbers (the biggest one, just discovered, has more than six million digits!) at this comprehensive website. CoolNumbers will now identify if your bill is a prime number.

Numbers In The News (Links are to .txt files)
Stories from The New York Times

Where's George
http://www.wheresgeorge.com
A fun website that will track where dollar bills have been. Users are encouraged to input their own dollar bills to get a history of its whereabouts.

Constants in Mathematics
http://www.abc.se/~m9847/matre/constans.html
http://numbers.computation.free.fr/Constants/constants.html
A list and explanation of constants that are frequently encountered in mathematics can be found at these websites. The third one emphasizes computation of these constants.

Integer Sequences
http://www.research.att.com/~njas/sequences/index.html
Remember those questions like "What are the next three terms in the series 1, 1, 2, 3, 5, 8, 13, __, __, __"? Well this website seeks to create an encyclopedia of all types of integer sequences. Put in an integer sequence or keyword, and it finds a sequence, complete with a formula for generating the numbers in the sequence, and a bit of history associated with each one.

Benford's Law
http://mathworld.wolfram.com/BenfordsLaw.html
http://www.intuitor.com/statistics/Benford's%20Law.html
For a very mathematical explanation of this fascinating pattern, visit MathWorld. For a simpler description, see Intuitor.