Hi Oliver,

First you need to determine how many 9 character passwords there are. If you start to write down all possible passwords you have 26 choices for the first character. Regardless of what character you chose you have 26 choices for the second character and hence 26 26 = 26² choices for the first two characters. Again, regardless of the choices for the first two characters you have 26 choices for the third character and thus 26³ choices for the first three characters. This procedure will give you the total number of possible passwords.

There are 1 000 000 = 10⁶ microseconds in a second so divide the total number of passwords by 10⁶ to determine the number of seconds it will take to test the passwords. You will then probably convert this to days, minutes and seconds.

How long will it take if a password consisted of a string of nine characters from the english alphabet or the ten digits 0 to 9 (36 characters)?

Penny