Answer:
Put the point a tiny bit more than half way between 14 and 15.
Explanation:
If you are allowed to use a calculator, put in sqrt215 and you get out 14.66, that goes a little bit more than halfway between 14 and 15.
If you are not allowed to use a calculator, think of the numbers on the numberline in terms of answers to *perfect square* questions.
So 12 is sqrt 144.
13 is sqrt 169.
14 is sqrt 196.
15 is sqrt 225.
So the 215 in your question is in between 196 and 225.
215 is closer to 225 (than to 196) so put the point closer to sqrt 225. That is, in between 14 and 15 and just a tad bit closer to 15.