HI Jim,

First I need to know how many square feet are in an acre. You can ask Google or any of the major search engines. I am a Mac user so I asked Siri.

Me: Hey Siri, how many square feet are there in one acre?
Siri: 1 acre is 43,560 square feet.

6 inches is half a foot so you need $\large \frac{1}{2} \normalsize \times 43,560 = 21,780$ cubic feet. But you want the answer in cubic yards. There are 3 feet in a yard and hence a cubic yard is 3 feet by 3 feet by 3 feet or $3 \times 3 \times 3 =27$ cubic feet. Thus you need

\[\frac{21,780}{27} = 806.7 \mbox{ cubic yards.}\]

Penny

Penny