How many small cubes, each having a surface area of $54 \mathrm{~cm}^{2}$, are needed to build a large cube with a surface area of $864 \mathrm{~cm}^{2}$?

(M. Krejčová)
A small cube has an edge length of $3 \mathrm{~cm}$. A large cube has an edge length of $12 \mathrm{~cm}$. To build the large cube, we need 64 small cubes.

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