Answer:
864 m³
Step-by-step explanation:
The volume is given by ...
V = LWH = (12 m)(12 m)(6 m) = 864 m³
864 cubic meters of water are required to fill the pool completely.
___
You could calculate this as 12²·6 or as 12³/2, or you can use your knowledge of powers of 12 to compute it as 144·6 or 1728/2.