Obelus
From Wikipedia, the free encyclopedia
- The word "obelus" is also an alternate name for the dagger (†) symbol.
An obelus (pl. "obeli") is a symbol consisting of a line with dots above and below, 
, used to represent the mathematical division operation. This symbol is also known as a division sign. Originally this sign (or a plain line) was used in ancient manuscripts to mark passages which were suspected of being corrupted or spurious. The word "obelus" comes from the Greek word for a sharpened stick, spit, or pointed pillar. This is the same root as that of the word "obelisk".
The obelus was first used as a symbol for division in 1659 in the algebra book Teutsche Algebra by Johann Rahn. Some think that John Pell, who edited the book, may have been responsible for this use of the symbol. The obelus had been used by some writers to represent subtraction, and that usage continued in some parts of Europe (including, until fairly recently, Denmark). The symbol had also been used occasionally in Polish language typography to represent ranges (such as 6–9), although this usage is mostly discontinued.
Today the obelus remains in occasional use, primarily as a standalone symbol for the division operation itself (as on a calculator), or as an operator in elementary arithmetic. In most contexts division is now signified in other ways, usually by writing the operands one above the other separated by a line, or on the same line with the slash (or solidus) as the symbol signifying division.
In the Unicode character set, the obelus is known as a "division sign" and has the code point U+00F7. In HTML, it can be encoded as ÷ (at HTML level 3.2) or ÷ or ÷. To enter an obelus on a Windows computer, hold down the Alt key as you type 0247 on the number pad. On a Macintosh, hold down the Option key as you type the slash (/) character.
