Question 1188237
<pre>
Are access codes like OOO00 allowed? Three letters "O" followed by two zeros "0"?

If so:

Choose the 1st character, a letter, 26 ways. Then:
Choose the 2nd character, a letter, 26 ways.
Choose the 3rd character, a digit, 10 ways.
Choose the 4th character, a digit, 10 ways.
Choose the 5th character, a digit, 10 ways. 

That's (26)(26)(10)(10)(10) = 676000 different access codes.

Edwin</pre>