Step-by-step answer:
We know that the square root of 16 is 4.
15 is one less than 16.
We also know that the square root of 9 is 3.
15 is 6 more than 9.
So by logic, we conclude that the square root of 15 is much closer to 4 than 3. So answer would be L, which is a touch less than 4.
If we want, we can actually get a very good estimate of the square root of 15, no paper, no calculators, as follows.
Our estimate is 4 (because 4^2=16, ONE more than 15).
Our BETTER estimate is 4- ONE/(twice our estimate)
= 4 - 1/8
= 3.875
(actual value 3.87298.. to 5 decimal places)
