Do We Teach Any Math in High School?

I am currently working to install pavers on the back patio of my home.  The previous owner had installed pavers without properly preparing the soil underneath, which caused the pavers to settle and become uneven over time.  To prevent this I have had to rip up the pavers and dig out a couple inches of the Devil's own soil, otherwise known as clay.  Next I will have to fill in the missing clay with coarse gravel (3/4" road base to be specific) and then re-lay the pavers.  Such are the joys of home-ownership.

This morning I called the local sand and gravel company to order the 20 cubic feet of gravel that I need to complete the next step of my project.  What follows is the conversation (as best I can reconstruct it) I had with Jim, the guy that takes phone orders for this company. 

Me:  I'd like to order 20 cubic feet of 3/4" road base please.
Jim:  I'm sorry, how many square feet do you want?
Me: I want 20 cubic feet.
Jim: We only sell in square feet.
I'm sorry, I want a volume of gravel, so I think that should be measured in cubic feet.
Well we only do square feet, like I said.
Ok, I'd like a volume of 3/4" road base that's 20 square feet across the top and 1 foot thick.
Our minimum order size is 100 square feet.
Ok, let's try this - how much does 100 square feet of 3/4" road base weigh?
I don't know. Let me ask somebody. (Puts me on hold for a couple minutes). Okay, sorry about that. 200 square feet of road base weighs 1 ton.
And how thick is that layer of road base spread over 200 square feet?
2"
(Pause for some quick math) Ok, then I want 128 square feet of 3/4" road base.

That's right - I ordered a volume of gravel in 2-D.  My 128 square feet of gravel will be delivered between 9 AM and 11 AM tomorrow morning.  I weep for the future.

(Note:  I originally wrote the I ordered 228 square feet in this post.  After several intelligent comments pointing out that I would have ordered far too much gravel that way, I went back and checked my order and I did, in fact, order "128 square feet" of road base.)