Numerology is an ancient system of divination that seeks information about a person's character and destiny, encrypted in their name and birth date.
The letters of a name are converted into numbers. Numerologists use different letter-to-number transformations (mappings) to do this. This calculator uses the Chaldean mapping of the alphabet, which excludes the 9 in the mapping (but uses it in the root) and alters the letter sequence. The simpler method, simply mapping the alphabet to the numbers 1 - 9 in a wrap around fashion, is known as Pythagorean Numerology - compare the results on this page with what you get using my Pythagorean Calculator. The very fact that you can have two different results should set alarm bells ringing.....
Once the number string has been produced, their digital root is calculated and the fortune is supposedly linked to that single digit number. Some numerologists use double digits and various other, more complex, methods.
Excellent information on numbers from Wikipedia, including mathematical and occult information: