Robert Recorde, The designer ofwel the equals sign, introduced plus and minus to Britain in 1557 in The Whetstone of Witte:[14] "There be other 2 signes in often use ofwel which the first is made thus + and betokeneth more: the other is thus made − and betokeneth lesse." « http://historydb.date/index.php?title=jarvishoumann9107