Painting the Silo - An Applied Mathematics Problem

I have to paint my silo and I need help. A can of paint comes in large (64 oz), medium (48 oz), and small (32 oz). The company scales the prices per ounce, so larger doesn't mean cheaper. One ounce covers about 1 square foot. To make it easier to transport, I do not want to buy extra paint, so help me figure out how many of each size I should buy.
Here is a rough drawing of my silo:

Can we figure it out?

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What kind of math teacher wouldn't answer this question?!?!
This problem is based on surface area. So, what is the surface area of a cylinder? To answer that, we break it up into the shapes of which it is made. A cylinder is made up of three pieces:

• 2 Circles (top and bottom)
• 1 rectangle (length is circumference and width is height):
  

Now just add up the areas:

The hard part here is that the length of the circle is 2πr, so lets sub that in with the numbers.

Since we have 2 circles and the rectangle we have: 78.5+78.5+628.3 = 785.3 sq. ft.

Now we need to know how much paint to buy.
12 Large cans paints 768 sq. ft.
1 Small cans paints 32 sq. ft.
Which covers it!

Hope you've enjoyed the cylindrical lesson Steemers! Happy trails and teach your kids!