# Is 20 a perfect square number?

Jul 5, 2015

No. It's root is $4.4721 \ldots$

#### Explanation:

You could have seen this without calculating in two ways:

${4}^{2} = 16$ which is too low
${5}^{2} = 25$ which is too high.

Or:
A square allways ends in an even number of zeroes. Every zero at the end means a factor 10, and in squares every factor is paired.