##27 in^3## or 27 Inches Cubed
The wording of this answer confused me but I think I might understand what it’s getting at.
In order to calculate the volume of a cube you need to know the length of a single side. If 9 blocks are required to find the volume then we must need all 9 blocks to measure a single side.
If we stack 9 block vertically (or line them up side by side) we get:
## 9 * 1/3in = 3in##
If a single side of the cube is 3 inches then we can simply solve for area using the area formula ##V = a^3##
##V = a^3 = 3^3 = 27in^3##