0.
A square foot is a measure of area (2 dimensions).
A cubic yard is a measure of volume (3 dimensions).
900 cubic feet would be 900/(3^3) = 900/27 = 100/3 = 33 1/3 cubic yards.
.
6 ft * 4 ft * 10 in
6 ft * 4ft * (5/6) ft
20 cubic ft
20/27 cubic yards