It's obvious and easy to know. 5280 feet in a mile. Just imagine how many steps you would need to take to walk a mile. 5280 steps, or feet. *nods*
(it's actually 2,000 steps in a mile, and the "easy" part is asking Google "How many feet are in a mile" and hoping Google gives you correct answer).
I have no concept of what 5280 feet look like.
Visualizes 1 feet.
Then imagines 5280 of those. Yep, means nothing to me.