Find the greatest 6 digit number which is a perfect square??

The greatest six digit number  = 999,999

we know that 1000² = 1,000,000 which is only 1 more than 999,999

 so  the greatest six digit number which is perfect square = (1000 -1)²

 = ( 999)² 

 = 998,001

Answer is 998,001.

Hope this helps you

thanks