# So much has come between us

I am better than my sister in every way!

For example, I am better at math. When it comes to rounding I get the correct answer more than half the time, while she gets the correct answer less often.

I even have my own fan base.

Sometimes I wear tights, but not my sister. She is sometimes covered in mites! Gross!

Maybe I'm just jealous though. My sister she is strong and can usually stand on her own, but I always seem to need support lest I fall to her level.

Who am I?

Who is my sister?

I think you and your sister are

ceiling and floor, respectively.

For example, I am better at math. When it comes to rounding I get the correct answer more than half the time, while she gets the correct answer less often.

For numbers with finitely many decimal places, and if you use the convention that things ending with exactly a 5 get rounded up, ceiling(x)=round(x) more often than floor(x)=round(x).

I even have my own fan base.

Ceiling fans.

Sometimes I wear tights, but not my sister. She is sometimes covered in mites! Gross!

Ceilings have stalactites and floors have stalagmites.

Maybe I'm just jealous though. My sister she is strong and can usually stand on her own, but I always seem to need support lest I fall to her level.

A ceiling without walls to support it would be in a lot of trouble.

• Good Job! This is exactly right. Commented Apr 13, 2018 at 17:39
• @YoungJohn Nitpick: there are many modes of rounding and lots of them do not round to +∞. In fact at least 2 of the commonly used ones (round half away from 0/round half to nearest even) have an equal distribution of round half up/down depending on your number range. It's not necessary (or even true!) that rounding up happens more than rounding down. Commented Apr 14, 2018 at 0:33
• Yup. You'll notice that I was quite specific in what I said about that bit :-). Commented Apr 14, 2018 at 1:21