It has always been the sign for number - I live at #302 in that building. I also has been used as the sign for pound - the bag of potatoes weighs 5#.

In the UK it's known as the hash symbol.

Anonymous How What do call this symbol? "#"

Number sign, pound sign, hash mark. (Those are the ones I've heard.)

CJ

The pound sign in British English is £.

Although the use of the hash (#) is not as rare as it used to be in BrE, we still generally use 'No(.)/no(.)'

fivejedjonThe pound sign in British English is £.

I knew that!

It reminds me of an American expression doesn't translate well into British: You look like a million bucks! (dollars), which is much more flattering than 'a million pounds'.

I'm not quite sure about this, but in music it is called sharp sign.

The sharp sign is a little different. Here is one from Word followed by the other thing: ? #

As well as "hash", "number sign" and "pound sign", the Wikipedia article (http://en.wikipedia.org/wiki/Number_sign#Other_names_in_English) lists numerous other names. (I mention this mostly for interest; many of the names are obscure and I don't recommend that you actually use them.)

I see, i thought it was the same. Thanks a lot

enoonThe sharp sign is a little different.

Right. The verticals in a sharp sign are always exactly vertical, whereas in the hash mark they usually have a bit of a slant. Conversely, the horizontals in a sharp sign are slanted upwards to the right, whereas those in the hash mark are exactly horizontal.

I think I'd probably write both of them the same