This calculator simulates the urn (or box with colored balls) often used for probability problems, and can calculate probabilities of different events.

This online calculator calculates posterior probabilities according to Bayes’ theorem.

This online calculator calculates the mean, variance, and standard deviation of random variables entered in the form of a value-probability table.

This online calculator takes a list of events along with number of times the particular event occurred and calculates the probability (and log probability) of each event by dividing event count to the total number of events.

This online calculator calculates measure known as fitness score, of how given text is similar to a typical English text. It uses logarithms of probabilities with normalization to calculate fitness score. The reference frequencies are calculated from Leipzig Corpora Collection and can be downloaded from http://practicalcryptography.com/cryptanalysis/text-characterisation/quadgrams/. The less value you get, the better.