No. - The Numero sign (U+2116) or Number sign is used in many languages to indicate ordinal numeration, especially in names and titles, for example, instead of writing the long "Number 4 Privet Drive" one would write the numero sign so: "№ 4 Privet Drive", and spoken as if written long.

Rbr. - redni broj - ordinal number - No.




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Note added at 11 hrs (2008-07-23 03:07:39 GMT)
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Also:

Number sign is a name for the symbol #; it is the preferred Unicode name for the code point associated with that glyph. Several other names for this symbol are used in the United States and Canada. In most other English-speaking countries, it is called a hash.
The number sign’s Unicode code point is U+0023, and its ASCII value is 0x23 (hexadecimal).
In many parts of the world, including Europe, Canada, Australia, New Zealand, and Russia, “number sign” is the name of the “número” sign № (Unicode code point U+2116), which is often written simply as No. In those countries, the # sign is not used to indicate a number.

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