* Cubic feet measure volume. Volume is the amount of space a three-dimensional object takes up.
* A dollar bill is two-dimensional. It has length and width but no significant thickness.
Think of it this way: You could stack a bunch of dollar bills on top of each other to create a block, and that block would have volume. But a single dollar bill itself doesn't have a measurable volume in cubic feet.
You could, however, measure the dollar bill in:
* Square inches or square centimeters: These units measure area, which is the space a two-dimensional object covers.
* Millimeters or inches: These units measure the thickness of the dollar bill.
