Recorde is known for introducing the "equal to" sign, i.e. "=". He published several mathematical works, including *The Grounde of Artes, teachings the Worke and Practise, of Arithmeticke, both in whole numbers and fractions* in 1543, which was the first book on Algebra published in England, and *The Whetstone of Witte, whiche is the seconde parte of Arithmeteke: containing the extraction of rootes; the cossike practise, with the rule of equation; and the workes of Surde Nombers*, in which he introduced the "=" sign.