Which of the following numbers are perfect squares?

$100, 205000, 3610000, 212300000$.

By just observing the digits at ones place, tell which of the following can be perfect squares?

$1026, 1022, 1024, 1027$.

How many non-square numbers lie between the following pairs of numbers?

$7^2$ and $8^2$.

How many non-square numbers lie between the following pairs of numbers?

${10}^2$ and ${11}^2$.

How many non-square numbers lie between the following pairs of numbers?

${40}^2$ and ${41}^2$.

How many non-square numbers lie between the following pairs of numbers?

${80}^2$ and ${81}^2$.

How many non-square numbers lie between the following pairs of numbers?

${101}^2$ and ${102}^2$.

How many non-square numbers lie between the following pairs of numbers?

${205}^2$ and ${206}^2$.

Observe the pattern in the following and find the missing numbers.

$$\begin{gathered} 121=\frac{{\left(22\right)}^2}{1+2+1} \\ 12321=\frac{{\left(333\right)}^2}{1+2+3+2+1} \\ 1234321=\mathrm{\_\_\_\_\_} \\ 123454321=\mathrm{\_\_\_\_\_} \\ 12345654321=\mathrm{\_\_\_\_\_} \end{gathered}$$