Number sign

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#
Number sign
Punctuation
apostrophe  '
brackets[ ]  ( )  { }  ⟨ ⟩
colon:
comma,  ،  
dash  –  —  ―
ellipsis  ...  . . .
exclamation mark!
full stop, period.
hyphen
hyphen-minus-
question mark?
quotation marks‘ ’  “ ”  ' '  " "
semicolon;
slash, stroke, solidus/  
Word dividers
interpunct·
space    
General typography
ampersand&
asterisk*
at sign@
backslash\
bullet
caret^
dagger† ‡
degree°
ditto mark
inverted exclamation mark¡
inverted question mark¿
number sign, pound, hash, octothorpe#
numero sign
obelus÷
ordinal indicatorº ª
percent, per mil% ‰
plus and minus+ −
basis point
pilcrow
prime    
section sign§
tilde~
underscore, understrike_
vertical bar, pipe, broken bar|    ¦
Intellectual property
copyright©
sound-recording copyright
registered trademark®
service mark
trademark
Uncommon typography
asterism
hedera
index, fist
interrobang
irony punctuation
lozenge
reference mark
tie
Related
In other scripts
 
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Not to be confused with the Chinese character (well), the sharp sign (), the viewdata square (), or the numero sign ().
#
Number sign
Punctuation
apostrophe  '
brackets[ ]  ( )  { }  ⟨ ⟩
colon:
comma,  ،  
dash  –  —  ―
ellipsis  ...  . . .
exclamation mark!
full stop, period.
hyphen
hyphen-minus-
question mark?
quotation marks‘ ’  “ ”  ' '  " "
semicolon;
slash, stroke, solidus/  
Word dividers
interpunct·
space    
General typography
ampersand&
asterisk*
at sign@
backslash\
bullet
caret^
dagger† ‡
degree°
ditto mark
inverted exclamation mark¡
inverted question mark¿
number sign, pound, hash, octothorpe#
numero sign
obelus÷
ordinal indicatorº ª
percent, per mil% ‰
plus and minus+ −
basis point
pilcrow
prime    
section sign§
tilde~
underscore, understrike_
vertical bar, pipe, broken bar|    ¦
Intellectual property
copyright©
sound-recording copyright
registered trademark®
service mark
trademark
Uncommon typography
asterism
hedera
index, fist
interrobang
irony punctuation
lozenge
reference mark
tie
Related
In other scripts

Number sign is a name for the symbol #, which is used for a variety of purposes, including (mainly in the United States) the designation of a number (for example, "#1" stands for "number one"). In recent years, it has been used for "hashtagging" on social media websites.

The term number sign is most commonly used when the symbol is used before a number. In the United States, it is sometimes known as the pound sign, and has been traditionally used in the food industry as an abbreviation for pounds avoirdupois. Outside of North America the symbol is called hash and the corresponding telephone key is called the "hash key" (and the term "pound sign" usually describes the British currency symbol "£"). The symbol is defined in Unicode as U+0023 # number sign (HTML: # as in ASCII).

The symbol may be confused with the musical symbol called sharp (). In both symbols, there are two pairs of parallel lines. The main difference is that the number sign has two horizontal strokes while the sharp sign has two slanted parallel lines which must rise from left to right, in order to avoid being obscured by the horizontal musical staff lines.

Origin and usage and naming conventions in North America[edit]

Mainstream use in the United States is as follows: when it precedes a number, it is read as "number", as in "a #2 pencil" (spoken aloud as: "a number-two pencil"). A theory claims that back in early 1900s, the Teletype Corporation was the first to use # to mean "number".[1]

When the symbol follows a number, the symbol indicates weight in pounds. (Five pounds are indicated as 5#.)[2] This informal usage still finds handwritten use, and may be seen on some signs in markets and groceries. It is often claimed that the pound symbol derives from a series of abbreviations for pound, the unit of weight. The theory goes that at first "lb." was used; however, printers later designed a font containing a special symbol of an "lb" with a line through the verticals so that the lowercase letter "l" would not be mistaken for the numeral "1". Unicode character U+2114 l b bar symbol (HTML: ℔) is a cursive development of this symbol. Ultimately, the symbol was reduced for clarity as an overlay of two horizontal strokes "=" across two forward-slash-like strokes "//".[3] Keith Gordon Irwin, in The Romance of Writing, p. 125, says "The Italian libbra (from the old Latin word libra, 'balance') represented a weight almost exactly equal to the avoirdupois pound of England. The Italian abbreviation of lb with a line drawn across the letters [℔] was used for both weights.

An alternative theory is that the name “pound sign” is a result of the fact that character encodings have historically used the same code for both the hash symbol and the British pound sign "£". It is sometimes supposed that the problem originated in ISO 646-GB, but it seems more likely that it has its origin in Baudot code in the late 19th century.[1]

In Canada the symbol is commonly called the number sign. Major telephone-equipment manufacturers, such as Nortel, have an option in their programming to denote Canadian English, which in turn instructs the system to say "number sign" to callers instead of "pound sign".

Usage in the United Kingdom and Ireland[edit]

In the United Kingdom and Ireland, the symbol is most often called the hash (a corruption of "hatch",[4] referring to cross-hatching). It is never used to denote pounds weight (lb is used for this non-metric unit) or pounds sterling (where "£" is used). It is never called the "pound sign", because that term is understood to mean the currency symbol "£", for pound sterling or (formerly) Irish pound.

While the use of "#" as an abbreviation for "number" may be understood in Britain and Ireland by some, it is generally not used. Where Americans might write "Symphony #5", the British and Irish are more likely to write "Symphony No. 5", or perhaps use the numero sign "Symphony № 5".

To add to the confusion between "£" and "#", in BS 4730 (the UK national variant of the ISO/IEC 646 character set), 0x23 represents "£" whereas in ASCII (the US variant), it represents "#". It was thus common, when systems were incorrectly configured, for "£" to be displayed as "#" and vice versa.

Other names in English[edit]

The symbol has many other names (and uses) in English:

Comment sign 
Taken from its use in many shell scripts and some programming languages (such as Python) to start comments.
Cross 
In China, non-native English speakers often refer to the number sign as "cross". It is said as jĭng in Chinese, as it looks like the Chinese character for water well ("井").
Hex 
Common usage in Singapore and Malaysia, as spoken by many recorded telephone directory-assistance menus: 'Please enter your phone number followed by the hex key'. The term 'hex' is discouraged in Singapore in favour of 'hash'. [clarification needed]
Octothorp, octothorpe, octathorp, octatherp
Used by Bell Labs engineers by 1968.[5] Lauren Asplund says that he and a colleague were the source of octothorp at AT&T engineering in New York in 1964. The Merriam-Webster New Book of Word Histories, 1991, has a long article that is consistent with Doug Kerr's essay,[6] in that it says "octotherp" was the original spelling, and that the word arose in the 1960s among telephone engineers as a joke. The first appearance of "octothorp" in a US patent is in a 1973 filing which also refers to the six-pointed asterisk (✻) used on telephone buttons as a "sextile".[7]
Sharp 
Resemblance to the glyph used in music notation, U+266F (♯). So called in the name of the Microsoft programming languages C#, J# and F#. However Microsoft says "It's not the 'hash' (or pound) symbol as most people believe. It's actually supposed to be the musical sharp symbol. However, because the sharp symbol is not present on the standard keyboard, it's easier to type the hash ('#') symbol. The name of the language is, of course, pronounced 'see sharp'."[8] According to the ECMA-334 C# Language Specification, section 6, Acronyms and abbreviations, the name of the language is written "C#" ("LATIN CAPITAL LETTER C (U+0043) followed by the NUMBER SIGN # (U+0023)") and pronounced "C Sharp".[9]
Space 
Used in proof-reading to denote that a space should be inserted. This can mean
  1. a line space (the space between two adjacent lines denoted by line # in the margin),
  2. a hair space (the space between two letters in a word, denoted by hr #)
  3. a word space, or letter space (the space between two words on a line, two letter spaces being ##)
Em- and en-spaces (being the length of a letter m and n, respectively) are denoted by a square-shaped em- or en-quad character ( and , respectively).[citation needed]
Square 
Occasionally used in the UK (e.g. sometimes in BT publications and automatic messages) – especially during the Prestel era, when the symbol was a page address delimiter. The International Telecommunications Union specification ITU-T E.161 3.2.2 states: "The # is to be known as a 'square' or the most commonly used equivalent term in other languages."
Others 
crosshatch, (garden) fence, mesh, flash, grid, pig-pen, tictactoe, scratch (mark), (garden) gate, hak, oof, rake, crunch, punch mark,[10] sink, corridor, and waffle.

In mathematics[edit]

In computing[edit]

In popular culture[edit]

Other uses[edit]

Unicode[edit]

In Unicode, several # characters are assigned:

In other languages or scripts:

Related characters, the sharp sign in musical notation:

On keyboards[edit]

On the standard US keyboard layout, the # symbol is Shift+3. On standard UK and some other European keyboards, the same keystrokes produce the pound currency symbol (£), and # is moved to a separate key above the right shift. On UK Mac keyboards, # is generated by Opt+3, whereas on other European Mac keyboards, the # can be found above the right shift key.

References[edit]

  1. ^ a b "The "pound sign" mystery". Retrieved 22 December 2012. 
  2. ^ William Safire (March 24, 1991). "On Language; Hit the Pound Sign". New York Times. Retrieved May 21, 2011. 
  3. ^ Houston, Keith (2013-09-06). "The Ancient Roots of Punctuation". The New Yorker. Retrieved 16 October 2013. 
  4. ^ "Hash sign". Oxford English Dictionary. Retrieved 14 October 2013. 
  5. ^ Hochhester, Sheldon (2006-09-29). "Pressing Matters: Touch-tone phones spark debate". Encore. 
  6. ^ Douglas A. Kerr (2006-05-07). The ASCII Character "Octatherp" (PDF). 
  7. ^ U.S. Patent No. 3,920,296, Google Patent Search
  8. ^ Frequently Asked Questions about C#
  9. ^ Ecma-international.com
  10. ^ http://ss64.com/bash/syntax-pronounce.html
  11. ^ "Introduction to HTML", W3C Recommendation
  12. ^ Lispworks.com
  13. ^ Oracle.com
  14. ^ "Scrabble Glossary". Tucson Scrabble Club. Retrieved 2012-02-06. 
  15. ^ Glossary of Medical Devices and Procedures: Abbreviations, Acronyms, and Definitions
  16. ^ Carnie, Andrew (2006). Syntax: A Generative Introduction (2nd ed.). Oxford: Wiley-Blackwell. ISBN 1-4051-3384-8.