Can you solve this connect the dots problem?
Suppose that you draw 10 dots and you want to connect them with lines so that every dot is connected to exactly 3 others. Can you come up with a strategy for doing this? It is okay if the lines cross each other.
This is a kind of aha! problem where, after thinking about it for a while, the answer comes all at once.
I suppose I could have made up a story around the problem, like having 10 people at a meeting arrange things so each person speaks to exactly 3 others, but the problem is easier to solve if you think of it in terms of dots and lines.
This question is in the General Section. Responses must be helpful and on-topic.