24 by 72 by 18 in cubic feet

I have to assume that the 24, the 72, and the 18 are feet.

If those are the dimensions of a rectangular prism, like a box, a crate,

or a humongous block of ice, then

Volume = (length) x (width) x (height) =

(24-ft) x (72-ft) x (18-ft) = 31,104 cubic ft

If those numbers are inches, then here's the easy way to handle it:

24 inches = 2 ft

72 inches = 6 ft

18 inches = 1.5 ft

Volume = (length) x (width) x (height) =

(2ft) x (6ft) x (1.5ft) = 18 cubic feet