Yes, 81 cubes can be arranged in a flat pattern of 9 columns of 9 cubes.
Yes, it can and it is.
4
27....
81 is einundachtzig in German.
8 square cm
quatre vingt-un
0.081
square
Cubes are prisms that have squares as bases and the height is the same as the edges. A square prism has square bases, top and bottom, and parallelograms as sides. A square pyramid has a square base and triangles for the vertical sides.
Cubes have a square on each side, but rectangular prisms have rectangles or squares.
A rectangular prism.
Every number has a square root and cube root. e.g. 2^(1/2) = 1.414213562..... 2^(1/3) = 1.25992105..... Both are irrational AND RECUR TO INFINITY. Similarly every other number.