There are 15,840 feet in 3 miles.
For every 1 mile there are 5,280 feet so you would take 5,280 miles and multiply that number by 3 and you get 15,840 feet for every 3 miles.
For every 1 mile of distance there are 5,280 feet.
Every mile that you drive or walk you're are going a distance of 5,280 feet which is pretty far especially when you're walking.
A mile of walking is some good exercise and 1 mile of driving seems pretty fast when driving.
For 2 miles there are 10,560 miles and for 3 miles there are 15,840 feet.
And so on and so forth.
To find out how many feet are in each mile take the 5,280 and multiply it by how many miles you're wanting to know the feet in distance and you'll get your answer.