Understanding Your FICO Score

Do you ever wonder how the three credit bureaus, TransUnion, Equifax, and Experian, come up with your FICO score?  Why do they all come up with a different score?  Shouldn't it just be one number?  They have different formulas to create a number, a number which plays a major role in a person's life.  Understanding what they use as their criteria to formulate a score is helpful to achieve the highest FICO score possible.  Many people think the bureaus use more than they do to determine a score, but they are a "credit bureau" and is only interested in is what credit they have had, have now, and how well they manage their credit.  True story: A friend of mine who has a considerable amount of money in investments, owns his own home and car, and owes no one.  Sounds responsible no?  He has zero credit and can buy nothing on credit.