Hi Javall. we can't do the maths either, being in inches not millimeters and being a rectangular box shaped measurement, not a board shaped measurement with rails contours etc. No can do!
The actual shape of the board within the measurements is the final arbiter of volume.
Go to somewhere like the firewire site or any other site that shows volume calculators and check out something similar on their sites.
Failing that post a picture of the board

Tell us how experienced you are, what you weigh, and what your volume is, maybe then we can advise you.
The real question you need to ask is; Will this board surf well for me at my level?