$A$ cuboidal box measures $25 \, cm \times 15 \, cm \times 8 \, cm$. Find its total surface area (in $cm^2$).

$A$ cone is $8.4 \, cm$ high and the radius of its base is $2.1 \, cm$. It is melted and recast into a sphere. The radius of the sphere is (in $cm$):

$A$ metal sphere of radius $20\, cm$ is melted and then cast into small hemispheres each of radius $5\, cm$. Find the number of hemispheres thus obtained (in balls).

Curved surface area of a cone $= \dots$

Total surface area of a hemisphere $= \dots$

If the edge of a cube is $7\, cm$,find its total surface area in $cm^2$.