We are asked to memorize the 7 default routes created when we define a single entry in the routing file, for example resources :posts.
This is how I memorized the 7 routes and the 4 helpers in the Rails guides:
I used posts as an example of a resource and reorganized the table shown in the guide in a way that makes sense to me.
There are 4 paths, 4 helpers, and 7 routes. I know the verbs (methods) under each path must be unique, i.e., there can't be two GET requests to /posts that route to two different actions. I fill in the verbs first, then their associated actions.
Finally, I write down the order in which the actions appear, by convention, in the controller file.