We can use the fact that the diagonal of a square with side [tex]s[/tex] measures [tex]s\sqrt{2}[/tex].
So, if you build the square with vertices
[tex]A=(0,0),\quad B=(0,2),\quad C=(2,0),\quad D=(2,2)[/tex]
The sides have length 2, and thus the diagonal AD is exactly [tex]2\sqrt{2}[/tex] units long.
Now, center a compass at A, and open it until you reach D. Draw the circle until you reach the x axis.
Since the circle has radius [tex]2\sqrt{2}[/tex], you will meet the x axis exactly at point [tex]E=(2\sqrt{2},0)[/tex], and you've drawn the point on the number line.
