Robert Recorde (c. 1510 – 1558) was a Welsh physician and mathematician. He introduced the "equals" sign (=).

A member of a respectable family of Tenby, Wales, he entered the University of Oxford in about 1525, and was elected a fellow of All Souls' College in 1531. Having adopted medicine as a profession, he went to the University of Cambridge to take the degree of M.D. in 1545. He afterwards returned to Oxford, where he publicly taught mathematics, as he had done prior to going to Cambridge. It appears that he afterwards went to London, and acted as physician to King Edward VI and to Queen Mary, to whom some of his books are dedicated. He was arrested for debt and died in the King's Bench prison, Southwark, in 1558.

Recorde published several works upon mathematical subjects, chiefly in the form of dialogue between master and scholar, such as the following:

• The Grounde of Artes, teachings the Worke and Practise, of Arithmeticke, both in whole numbers and fractions (1540)
• The Pathway to Knowledge, containing the First Principles of Geometry ... bothe for the use of Instrumentes Geometricall and Astronomicall, and also for Projection of Plattes (London, 1551)
• The Castle of Knowledge, containing the Explication of the Sphere both Celestiall and Materiall, etc. (London, 1556)
• The Whetstone of Witte, which is the second part of Arithmetike, containing the Extraction of Rootes, the Cossike Practice, with the Rules of Equation, and the Woorkes of Surde Numbers (London, 1557). This was the first English book on algebra.
• a medical work, The Urinal of Physic (1548), frequently reprinted.

Sherburne states that Recorde also published Cosmographiae isagoge, and that he wrote a book De Arte faciendi Horologium and another De Usu Globorum et de Statu temporum. Recorde's chief contributions to the progress of algebra were in the way of systematizing its notation.

The = symbol that is now universally accepted for equality was first used by Robert Recorde in The Whetstone of Wit (1557). According to the St Andrews Math History site[1] (http://www-history.mcs.st-and.ac.uk/Mathematicians/Recorde.html),"He justifies using two parallel line segments: ... bicause noe 2 thynges can be moare equalle ". They also point out that " The symbol = was not immediately popular. The symbol || was used by some and ae ( or oe), from the word 'aequalis' meaning equal, was widely used into the 1700s."

See also

Zenzizenzizenzic- a word to describe a number to the eighth power coined by Robert Recorde.

This article incorporates text from the public domain 1911 Encyclopædia Britannica.

External links

• McTutor biography (http://www-gap.dcs.st-and.ac.uk/~history/Mathematicians/Recorde.html)