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 twee signes in often use of which the first is made thus + and betokeneth more: the other is thus made − and betokeneth lesse." « https://sparktv.net/post/277484_https-nl-wikipedia-org-wiki-kwaliteit-https-foliemolie-nl-https-foliemolie-nl-ee.html