Serial numbers for a product are to be made using 4 letters followed by 2 digits. The letters are to be taken from the first 6 letters of the alphabet, with no repeats. The digits are taken from the 10 digits 0, 1, 2, ..., 9, with no repeats. How many serial numbers can be generated?
+202 Let's use constructive counting to find the answer. There are 6 choices for the first letter, then 5, and so on. For the numbers, there are 10 choices for the first number, and 9 for the second. Since these choices are independent of each other, we can multiply these numbers together. Does my explanation make sense?
