# How to label the 13th floor     4.27 (22 votes) Loading... ### 9 thoughts on “How to label the 13th floor”

1. Further evidence that explaining the joke ruins it.

2. Except that the absolute value is unnecessary, the square root of 169 is 13, it can’t be -13, otherwise square root wouldn’t be a function.
So the joke is more of a fail.

1. I hope you’re not serious and/or a math major.

1. Negative numbers can be roots. There is no general requirement that the square root operator has to be a function. You can declare it to be a function by restricting the domain to positive numbers, or you can put the absolute value sign in. Either way works. But the original commenter who wrote root(169) did neither, so unqualified, BOTH -13 and 13 are roots of 169.

1. Using the square root symbol denotes the principal square root, which is always positive. Thus the absolute value is not needed. For example, this is why there is a Â± in the quadratic formula.

And yes f(x) = sqrt(x) is a function.

http://en.wikipedia.org/wiki/Square_root

2. BtaylorTheRogue

I’m not great at math, but I don’t think square root IS a function, strictly speaking. . . or at least not a simple function (if simple function is a thing that exists).

Also, lolwut?

3. 12′

4. http://en.wikipedia.org/wiki/Square_root

The second and third paragraphs explain this. The square root sign denotes the positive square root. If you are referring to the negative root, you just put a minus sign in front of it. If you are referring to both roots, you use the Â± sign. 🙂