Arabic Mathematical Looped Dad

It is a letter form, not an operation sign.

Its base letter is ḍād (ض), a consonant used in Arabic-based scripts. Arabic mathematical notation uses distinct letter styles as part of its meaning, so this looped form can remain distinct from other letters in a formula. Read its role from the expression around it.

How did Arabic letters enter mathematics?

Arabic mathematical styles descend from letter forms used in manuscripts and traditional print. Algebraic notation had emerged in the Maghreb by the end of the 12th century. In the 15th century, al-Qalasadi used Arabic word initials such as ج, from جذر (jadhr, “root”), for a square root and ش, from شيء (shayʾ, “thing”), for an unknown.

Regional conventions differ: a 2006 description of Mashreq and Maghreb notation records different Arabic letters for sum and function. As of Unicode 18.0, Arabic-script mathematical alphabets appear in most mathematical handbooks published in West Asia, Libya, and Algeria; they are also used with scripts such as Arabic and Persian.