Question 106017
3 digit number less than 200
{{{100<=N^2<200}}}
Let’s look at the possible perfect squares in this range
{{{10^2=100}}}
{{{11^2=121}}}
{{{12^2=144}}}
{{{13^2=169}}}
{{{14^2=196}}}
Let’s look at those squares with digits reversed
001 – Perfect square {{{(1^2)}}}
121 – Perfect square {{{(11^2)}}}
441 – Perfect square {{{(21^2)}}}
961 - Perfect square {{{(31^2)}}}
691 – Not a perfect square
There are four matches 100, 121, 144, and 169 that work. 
However you also mentioned that no two digits can be the same. 
That leaves only 169 as the final answer.