Discrete Math
posted by Rob .
A factory makes automobile parts, 5C7, 1O6 or 3Z0, which are of 5,000 parts, what is the minimum number of parts with the same serial number?

Assuming all 26 letters are used, and the first and last are digits, i.e. NAN, where N=digits 09, A=letter AZ, there are, using the multiplication principle, 10*26*10=2600 distinct part numbers.
What is the minimum number of parts with the same serial number when there are 5000 parts and 2600 numbers available? 
5000