If we then have 5 characters in the password, the number of password combinations will be: aaaaa to ZZZZZ. which will be 52 to the power of 5 = 380,204,032. If we crack these passwords at a rate of one million per second then it will take 380 seconds to try all of them (6.23 mins). Here is the calcuation for [a-zA-Z] with one million password ...
Mar 01, 2004 · Pepsi may have made one or more of the numbers a check digit (reducing further the number of possible combinations) to confirm the winning number. That way they only need to keep a record of 1 (or a few) algorithms for calculating the check digit based on the other digits in the code, instead of keeping 100 million records in the database.