Exercises: Square Roots

The next square numbers with respect to 20 are:

The number 20 lies between the square numbers 16 and 25, so you know about the square root of 20 that

I.e., $\sqrt{20}$ lies between the natural numbers $4$ and $5$.

Since the square numbers 16 and 25 have approximately the same distance to 20, you know that the number $\sqrt{20}$ is approximately in the middle of 4 and 5.

So, the square root of 20 is approximately 4.5.