Answer: 169.
Justification.
A perfect square is a number that can be expressed and the square of an integer.
[tex]169=13^2=13*13[/tex]
It is a good idea to memorize the first perfect squares. I sugest you memorize the squares of the numbers from 1 to 14, it will help you a lot in some standardized tests,which requires to answer some quesitons fast:
[tex]1^2=1
2^2=4
3^2=9
4^2=16
5^2=25
6^2=36
7^2=49
8^2=64
9^2=81
10^2=100
11^2=121
12^2=144
13^2=169
14^2=196[/tex]
