A part has a code consisting of a digit, a letter, and a digit, such as 5C7 or 9G2. The factory made 5000 parts. Find the minimum number of parts that must have the same serial number.
Assuming that a part could be numbered 0U0, digits can be repeated.
There are 2600 different ways to label the parts. Thus this is a variation of a pigeonhole problem. Hence, how many parts might have the same label as another?