Robert Recorde, The designer ofwel 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 is made thus + and betokeneth more: the other kan zijn thus made − and betokeneth lesse." https://barnett-mcneil-4.blogbright.net/een-eenvoudige-sleutel-voor-wrapfolie-tafel-onthuld