Ellis is painting wooden fenceposts before putting them in his yard. They are each 6 feet tall and have a diameter of 1 foot. There are 12 fenceposts in all. How much paint will Ellis need to paint all the surfaces of the 12 fenceposts? Use 3.14 for π, and round your answer to the nearest hundredth. Provide an explanation and proof for your answer to receive full credit.

My answer so far:
First, what I want to do is get all the measurements in the same form. Since the radius of 1 ft diameter is 6 inches, I need to convert the height into inches. To do this, I multiply 6*12=72. So, each post is 72 inches tall. Now, I use the surface area formula for a cylinder. Then I plug in the numbers from this problem to get 2(3.14)(36)+2(3.14)(6)(72). Now, I do all this multiplying and adding to get 2,939.04 square inches

I NEED HELP PLEASE