
Steven S. answered 07/19/22
Experienced Tutor Specializing in Probability and Statistics
I like to think of this problem as figuring out how many choices I have for each "slot." Per the problem statement, it looks like there are 7 total slots.
For the first slot, there are 10 numbers to choose from (0-9).
For the second slot, there are 26 letters to choose from (A-Z).
You can repeat this procedure for the rest of the slots. To find the total, multiply all the numbers together.