[PAR35]

A 60’ x ‘60’ x 60’ cube is 216,000 square feet

You might want to look at that carefully and revise it. Spot your error yet? (Hint, what would the height of your cube be if it was 216,000 square feet but had the volume of a 60x60x60 foot cube?)

[PAR35]

Here’s another clue:

500 x 432 feet would give you your 216,000 footprint (other number would also work.) If x*y=216,000 square feet,
x*y / (60*60*60) = z, with z being a constant.

[Mr. Jeeves]

You are the math equivalent of a Spelling Nazi. :)