What is the area of the shaded portion if each side of the square measures $21\,cm$? (in $cm^2$)

An isosceles right-angled triangle has an area of $200 \, cm^2$. The length of its hypotenuse is ..... $cm$.

How many cubes of edge $3\, cm$ can be cut out of a wooden cube of edge $9\, cm$?

The cost of levelling a rectangular ground at $Rs. 1.25$ per $sq. metre$ is $Rs. 900$. If the length of the ground is $30$ $metres$,then the width is? (in $metres$)

The diameters of two concentric circles are $8\, cm$ and $10\, cm$. The area of the region between them is

The dimensions of a field are $20 \text{ m}$ by $9 \text{ m}$. $A$ pit $10 \text{ m}$ long,$4.5 \text{ m}$ wide and $3 \text{ m}$ deep is dug in one corner of the field and the earth removed has been evenly spread over the remaining area of the field. What will be the rise in the height of the field as a result of this operation? (in $m$)