Find the greatest number of six digit which is a perfect square.

From the ques, it can be said that the answer would be less than 1000000

Start from 999,

999*999 = 998001

Therefore, 998001 is a greatest number of square 999.

A "perfect square" is an integer that is the square of an integer.

The largest 6-digit integer is 999,999.

The square root of it is 999.9995

So the greatest square of an integer is the square of 999 = 998,001.