<P> An alternative theory is that this name arose from the fact that character encodings used the same code for both the number sign and the British pound sign "£". Claims have included ISO 646 - GB as well as the Baudot code in the late 19th century . The apparent use of the sign to mean pounds weight in 1850 appears to rule out both of these code sets as the origin, although that same reference admits that the earliest reference in print was a decade after Baudot code . </P> <P> "Hash sign" is found in South African writings from the late 1960s, and from other non-North - American sources in the 1970s . </P> <P> Mainstream use in the United States is as follows: when it prefixes a number, it is read as "number", as in "a #2 pencil" (indicating "a number - two pencil"). The one exception is with the #key on a phone, which is always referred to as the "pound key" or "pound ." Thus instructions to dial an extension such as #77 are always read as "pound seven seven ." </P> <P> When the symbol follows a number, the symbol indicates weight in pounds . (Five pounds are indicated as 5 #.) This traditional usage still finds handwritten use, and may be seen on some signs in markets and groceries . It is also commonly known as the "pound sign". </P>

What is a pound key on your phone