First, we need to identify the square root of the fisrt squared numbers:
[tex]\begin{gathered} \sqrt{1}=\text{ 1} \\ \sqrt{4}=2 \\ \sqrt{9}=3 \\ \sqrt{16}=4 \\ \sqrt{25}=5 \\ \sqrt{36}=6 \\ \sqrt{49}=7 \\ \sqrt{64}=8 \end{gathered}[/tex]Since 40 is a number between 36 and 49, we can say that the square root of 40 is between 6 and 7. So:
[tex]6<\sqrt{40\text{ }}<7[/tex]