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This tag is for questions involving square numbers. A non-negative integer $n$ is called a square number if $n = k^2$ for some integer $k$. Consider using with the [elementary-number-theory] or [number-theory] tags.

A number $$n$$ is a square number if and only if it is the square of an integer. That is, if $$n = k^2$$ for some integer $$k$$.

The name square number, or perfect square, comes from the fact that these particular numbers of objects can be arranged to fill a perfect square.

The square numbers begin $$0, 1, 4, 9, 16, 25, 36, 49, ...$$

The $$k$$th square number is given by $$k^2$$ with the zeroth square being $$0$$. Square numbers are strictly non-negative as $$k^2 \ge 0$$ for all real $$k$$. There are $$\lfloor \sqrt{n} \rfloor+1$$ square numbers in the range $$[0, n]$$.

References:

https://en.wikipedia.org/wiki/Square_number