Check whether $36000$ is perfect square.

Check whether $1500$ is perfect square.

Check whether $9\times {10}^7$ is perfect square.

Check whether $16\times {10}^{24}$ is perfect square.

What is the square of $21$?

Look at this method:

$2^2=1^2+\left(1+2\right)$

$3^2=2^2+\left(2+3\right)$

Using the above method, find the square of $51$.

Look at this method:

$2^2=1^2+\left(1+2\right)$

$3^2=2^2+\left(2+3\right)$

Using the above method, find the square of $61$.

Look at this method:

$2^2=1^2+\left(1+2\right)$

$3^2=2^2+\left(2+3\right)$

Using the above method, find the square of $121$.

Look at this method:

$2^2=1^2+\left(1+2\right)$

$3^2=2^2+\left(2+3\right)$

Using the above method, find the square of $1001$.