Question 754168
<pre>
&#8730;<span style="text-decoration: overline">13</span> is approximately 3.6 which is a little more than half way between 3 and 4,
so you just sort of guess about where that is between 3 and 4 and put a dark
circle there:

{{{number_line( 600, -4, 6,  sqrt(13) )}}}

Edwin</pre>