### Video Transcript

Write a positive integer whose
square is between 120 and 130.

An integer is a whole number. Therefore, the positive integers
are one, two, three, and so on. Squaring a number involves
multiplying a number by itself. The first 10 square numbers are
one, four, nine, 16, and so on. This is because one squared is
equal to one, two squared is four, and three squared is nine.

We need to find a square number
between 120 and 130. 10 squared is equal to 100, which
is too small. 11 squared is equal to 121, which
does lie between 120 and 130. When we square the next positive
integer, 12, we get 144, which is too big. The only square number between 120
and 130 is 121. Therefore, the correct answer is
11.