Is the set of the months of the year null or not?
Remember that in maths, a set is a collection of things that have a common property. And we can write sets in between a pair of braces, like this. In this question, we’re asked to think about the set of the months of the year. So in between our braces, we’d expect to see all the names of the months of the year. So we might expect the set to look something like this. It contains 12 elements. January, February, March, April, May, June, July, August, September, October, November, and December. Our question asks whether the set of the months of the year is null or not.
We need to remind ourselves what the word null means. A null set is a set without any elements in it. We call this an empty set. And the way we write the notation for an empty set is using our braces but with nothing in between, like this. So is the set of the months of the year null or not? It’s not null. It contains 12 different elements that we talked about already. It contains all the different months of the year. Perhaps an example of a null set to do with the months of the year might be a set of all the months of the year that begin with the letter z. That would be an empty set. But the set of the months of the year is not null.