Jayashri Bhattacharya and Tarika Dhawan Solutions for Exercise 4: MENTAL MATHS

$1 \mathrm{cm}$ is equal to $10 \mathrm{mm}$. How many square $\mathrm{mm}$ are there in $1$ square $\mathrm{cm}$?

If the length and breadth of a rectangle are doubled, then its perimeter is

The perimeter of a square whose area is $2500$ is 

A rectangle made of wire has a perimeter of $60 \mathrm{cm}$. What is the length of each side if the wire is rebent to form a regular pentagon? 

Find the side of a square whose perimeter and area are the same.