Three solid cubes with edges 3 cm, 4 cm and 5 cm are melted together and recast as one larger cube. Find the edge of the new cube.

Both are repeated multiplication, but with key differences:

- A square is non-negative: $(-5{)}^2=+25$.
- A cube **keeps the sign**: $(-5{)}^3=-125$. (Three negatives stay odd → still negative.)
- Squares grow more slowly than cubes: $5^2=25$ vs $5^3=125.-$ For square roots, only positive results (by convention). For cube roots, the sign matches the input: ∛$(-27)=-3$.