Number Sign – Rules and Examples

The number sign can be more than just a symbol to indicate numerical uses. It also is known by multiple names and has a long history of use in computer programming and alternative communication via modern media. 

Look at how you can use this common typographical mark to help showcase numbers, designate comments in computer language, and highlight media information. Our guide below explains the usage and examples of ways to use this popular mark. 

What is the Number Sign?

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The number sign (#) is a typographical symbol that represents the word “number” in American English and in Canada. Generally placed immediately before a number or series of digits (with no spaces), it also is known by many other names and offers various other uses. 

For example:

  • Number one = #1

Octothorpe

The octothorpe is the official name for the # symbol and is a made-up word used in association with Bell Laboratories. In the 1960s, the telephone keypad was modified to include the number sign as a means to send instructions to the operating system. 

The name is believed to be composed of the word octo (meaning eight) and the Old Norse word thorpe, which means field or farm. 

Pound Sign/Key

Also known as the pound phone symbol or key on a telephone or mobile phone, automated phone systems often ask you to follow numbers with the pound key to indicate the end of your entry. The name is derived from the abbreviation for weight, lb, which comes from the Latin libra pondo (pound by weight). The writing of this unit of weight was often crossed with a horizontal line and looked like our modern number sign. 

For example:

Please enter your date of birth followed by the pound sign.

  • 06091978#

Hash

The hash symbol is the British version for the pound key since the Pound is the name for the British currency. The term is derived from the stripes on a military uniform, once referred to as a hash. This practice began in the early 1900s, but the hash didn’t refer to the # symbol until the 1980s. 

Hashtag

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Hashtag is derived from the British name for the hash key and is now used as a metadata tag or label in blogging and social media filtering of information. The use of a hashtag preceding specific words and phrases (sans spaces) is a popular way to show support or spread awareness in posts and comments, or find information and pictures related to the hashtag tag. 

Remember that the pound sign goes before the number or words with no spaces in this use. 

It has become prevalent enough in spoken language that it was added to the Oxford English Dictionary in 2014.

For example:

  • #2020Olympics
  • #GoodGrammar

How Else is the Number Sign Used?

Although the use of the number sign is generally specific to the alternative name associated with it, as seen above, there are some other uses the # sign is associated with. 

  • Musicians use the # sign as a sharp symbol.
  • Copy editors use the # key to denote the addition of a space needing to be added between two sentences. 
  • Editors and proofreaders use the # symbol as a proofreading mark to designate an insertion of a space needs to be included. 
  • Computer programmers use the hash to indicate everything following the command as a comment in the programming language. It is also used for scripting languages in a programming text.
  • Editors and journalists use a series of marks (###) to signify the end of a press release.

Where is the Number Sign on a Keyboard?

The number sign on an American keyboard layout is located on the number 3 key. It is accessed by holding the shift key and pressing the #3 key. 

On a telephone keypad, the pound key is located on the bottom right of the phone. 

Let’s Review

The number sign is a universal typographical symbol that offers information pertaining to both numbers and information. In American English, the # sign stands for “number” and is used as a replacement for the word in informal writing situations. It’s also used on a telephone keypad, where it is called a pound sign, to end the entry of numbers in automated phone systems. 

Outside its original use, it has become a popular way to delineate and filter information in editing, computer programming codes, and, most recently, social media.