Answer: 64
Explanation:
By definition, a perfect square is the square of a whole number.
The information given in the problem that you must keep on mind is:
- The number has two digits.
- The number is a perfect square ( Is obtained by squaring a whole number).
- The sum of its two digits is 10.
The number 64 is formed by the digit 6 and the digit 4. The sum of both digits is:

The number 64 can be written as:

Then, it is perfect square.