Obelus

Obelus , obel ( ÷ ) ( Latin obelus - from the Greek. Ὀβελός , the same root as the obelisk ) is a non-letter symbol that looks like a combination of minus and colon signs.

It was introduced by the ancient Greek philologist, Alexandrian librarian Zenodotus of Ephesus to indicate the doubtfulness of a word or statement. The symbol could look like either a regular horizontal line or the same line, but with the addition of points one at the top and bottom. It was put in the margins opposite to those parts of the text that were doubtful during the verification of the manuscripts received by the library.

In 1659, the German mathematician Johann Rahn in his work Teutsche Algebra used the obelus to indicate division . Some authors used this symbol as a subtraction sign, which has become the norm in several European countries (for example, Norway and Denmark ). In the Polish printing tradition, the obelus was used to indicate ranges, for example, the notation 3–7 is equivalent to the expression “from three to seven”.

In English-speaking countries, as well as on the keys of microcalculators , the obelus is used as a division mark . In TeX, it is encoded by: \ div.