is the old name for the process of reckoning with Arabic numerals. In mediaeval treatises the word is spelt in various ways: e.g. Algorismus , Alchoarismus , Alkauresmus , etc., corruptions of the nisba of the oldest known writer on Arabic arithmetic: Muḥammed b. Mūsa al-Ḵh̲^wārizmī [q.v.]. His book was translated into Latin in the 12th century by an unknown author, and the only known copy at Cambridge has been edited by B. Boncompagni ( Trattati d’aritmetica i, Rome 1857). It opens with the words: "dixit Algorithmi", the word is here correctly given in the form of an Arabic nisba, i.e. as a p…