so, hmm notice the picture below
a cube is just a rectangular prism, with all equal sides, if one side is 24, all are 24
now, the base of the largest pyramid then, is just a 24x24, and the height, will also be 24
thus [tex]\bf \textit{volume of a pyramid}\\\\
V=\cfrac{1}{3}Bh\qquad
\begin{cases}
B=\textit{base area}\\
h=height\\
----------\\
B=24\cdot 24\\
h=24
\end{cases}\implies V=\cfrac{1}{3}\cdot 24\cdot 24\cdot 24[/tex]