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 twee signes in often use of which the first is made thus + and betokeneth more: the other kan zijn thus made − and betokeneth lesse." https://cuwip.ucsd.edu/members/crownclick2/activity/486363/