Nakamura number

Okay kiddo, so you know when you go to a library and you see all the books arranged in different sections? Some books are about animals and some are about history, right?

Well, the Nakamura number is like a way to measure how closely related two books are based on how many sections between them. Imagine you have two books, one about dogs and one about birds. Since they are in different sections, they are "one section apart".

Now if we look at another pair of books, one about birds and one about insects, they are "two sections apart" since there is one section in between the bird book and the insect book.

So the Nakamura number is just a way of measuring how many sections there are between two different books in a library. And this number can be helpful for people who want to find related books or information that is similar to what they are already reading.