As the number of sets grows, we need more and more exotic shapes to portray them. One could reasonably argue that beyond four sets of elements, Venn diagrams lose their utility. The four-ellipse ...

Let’s add up the numbers we have so far in this circle: So 16 people are left over to go in the section that is blank. We can now fill this in on our Venn diagram. 16 visitors had seen Band X ...