Find the unique four-digit integer with these properties:
The last digit (the units digit) of is .
The digits of add up to .
Two digits of are the same.
is a perfect square.
Your question isn't fully complete.
The 4th clue alone narrows down the number to 68 possibilities, but we can not go any farther, because the question is incomplete.
Let me write it again
Find the unique four-digit integer with these properties:
The last digit (the units digit) of this four digit number is 9 .
The digits of the this four digit number add up to 27.
Two digits of this four digit number are the same.
is a perfect square.
Ok, now it is solvable. The first clue narrows the options down to 14 options: 1089, 1369, 1849, 2209, 2809, 3249, 3969, 4489, 5329, 5959, 6889, 7569, 8649, 9409.
After looking through all the possible options, we can narrow down our list furthur (the number must have 2 of the same digits) : 2209, 3969, 4489, 5959, 6889, 9409.
Looking through the list again, we see that only \(\color{brown}\boxed {3969}\) satisfies all 4 conditions.