How many small cubical blocks of side $5\, cm$ can be cut from a cubical block whose each edge measures $20\, cm$?

$A$ solid cylinder having a radius of base as $7 \, cm$ and length as $20 \, cm$ is bisected along its height to get two identical cylinders. What will be the percentage increase in the total surface area?

$A$ cube of lead with edges measuring $6\, cm$ each is melted and recasted into $27$ equal cubes. The length of the edge of the new cube is.......$cm$

If the side of a cube is increased by $100 \%$,its volume is increased by (in $\%$)

$A$ school room is to be built to accommodate $70$ children,so as to allow $2.2\, m^2$ of floor area and $11\, m^3$ of space for each child. If the room is $14\, m$ long,what must be its breadth and height?

The radius of the base of a hollow cone is $8\, cm$ and its height is $15\, cm$. $A$ sphere of the largest possible radius is placed inside the cone. What is the ratio of the radius of the base of the cone to the radius of the sphere?