Robert Recorde, The designer of the equals sign, introduced plus and minus to Britain in 1557 in The Whetstone ofwel Witte:[14] "There be other 2 signes in often use of which the first kan zijn made thus + and betokeneth more: the other is thus made − and betokeneth lesse." http://polimentosroberto.com.br/index.php?option=com_k2&view=itemlist&task=user&id=5679354