The specified digits are 8, 2 and 9. Now, we know a perfect square number does not have 8 and 2 at unit's place. Therefore, we can make only two three-digit numbers from it, i.e., 829 and 289. Among these two numbers, 289 is a perfect square number, i.e., square of 17. Thus, unit's digit is 7 and ten's digit is 1.