In this sheet, we will look at basic counting problems. The fundamental principle is quite simple. If you have to make two independent choices to make, the number of options for making both choices is calculated by multiplying the number of options for each choice.
A problem one immediately runs into is that of overcounting. This means we counted the same thing more than once. In the examples and problems today, you will see various ideas we can use to correct for overcounting or avoiding it.