Check the picture below.
[tex]\textit{volume of a pyramid}\\\\ V=\cfrac{Bh}{3}~~ \begin{cases} B=\stackrel{base's}{area}\\ h=height\\[-0.5em] \hrulefill\\ B=\stackrel{600\times 600}{360000}\\ h=300 \end{cases}\implies V=\cfrac{(360000)(300)}{3}\implies V=36000000~ft^3[/tex]