# Thread: Combination / permutation Question

1. ## Combination / permutation Question

Question:

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.

2. Originally Posted by oldguy
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?

3. Thanks, I got the same answer. Out of 5000 parts 2600 will have unique numbers and 2400 will not.