Is my book answer incorrect?

Hi,

I have a simple Volume problem that I would like some assistance with please: I have a Cylinder of Duct work measuring *6' long and 6" (diameter) or height*. I need the Volume of aire inside it so I am using the following formula: $\displaystyle V = pi r^2 h$

$\displaystyle V = (3.141592)(3in)^2 (72in)$

$\displaystyle V = (3.141592)(9in)(72in)$

$\displaystyle V = (3.141592)(648)$

$\displaystyle V = 2035.75"^2$

Now my book has an answer of $\displaystyle 1.2^3$ feet.

What in the world am I doing wrong? (Thinking)

I am so confused here. If only the book would give more than just an answer...

TIA,

GA