Question

Find the greatest $4$ digit no which is a perfect square.

Answer 1

${100}^2\to 10000$ (smallest five digit no.).

$9999\to$ biggest $4$ digit no. but not a perfect square.

$\because {100}^2$ gives the smallest 5 digit no.

$\therefore {99}^2$ will give the biggest 4 digit no. which will be a perfect square. $(\because 99<100)$

${99}^2\to 9801\to$ greatest 4 digit no. which is a perfect square.