{"id":35333,"date":"2015-02-17T06:00:11","date_gmt":"2015-02-17T11:00:11","guid":{"rendered":"http:\/\/blog.uncommongoods.com\/?p=35333"},"modified":"2015-02-13T17:17:02","modified_gmt":"2015-02-13T22:17:02","slug":"uncommon-knowledge-invented-first","status":"publish","type":"post","link":"https:\/\/www.uncommongoods.com\/blog\/2015\/uncommon-knowledge-invented-first\/","title":{"rendered":"Uncommon Knowledge: Was + or = invented first?"},"content":{"rendered":"<p><a href=\"http:\/\/www.uncommongoods.com\/product\/math-formulas-tie?source=blog\" target=\"_blank\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-35347 aligncenter\" src=\"https:\/\/www.uncommongoods.com\/blog\/\/wp-content\/uploads\/2015\/02\/15820_FormulasTie-e1423865295109-548x628.jpg\" alt=\"Math Formulas Tie | UncommonGoods\" width=\"314\" height=\"360\" srcset=\"https:\/\/www.uncommongoods.com\/blog\/wp-content\/uploads\/2015\/02\/15820_FormulasTie-e1423865295109-548x628.jpg 548w, https:\/\/www.uncommongoods.com\/blog\/wp-content\/uploads\/2015\/02\/15820_FormulasTie-e1423865295109-300x343.jpg 300w\" sizes=\"(max-width: 314px) 100vw, 314px\" \/><\/a><\/p>\n<p>It seems hard to believe that +, = and all the other symbols of the mathematical world haven\u2019t always simply existed like they do now. But in fact, the plus sign didn\u2019t come around until the 15th century. A symbolic contraction of the Latin word <i>et<\/i>, meaning \u201cand,\u201d it took another hundred years or so for it to be widely adopted. Maybe it was that handy \u201cand\u201d sign that inspired Robert Recorde, in 1557, to use two parallel lines to represent \u201cis equal to.\u201d But if we know when these math symbols were invented, it brings up the question of what mathematicians were using before that. The horrifying answer? Story problems. Here is an actual question from a 9th century, Persian text about algebra: \u201cI have divided ten into two parts, and multiplying one of these by the other, the result was twenty-one.\u201d Shiver.<\/p>\n<p><a href=\"http:\/\/www.uncommongoods.com\/product\/math-formulas-tie?source=blog\" target=\"_blank\">Math Formulas Tie, $45<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>It&#8217;s hard enough to imagine math before calculators! <\/p>\n","protected":false},"author":32,"featured_media":35353,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1208],"tags":[813],"_links":{"self":[{"href":"https:\/\/www.uncommongoods.com\/blog\/wp-json\/wp\/v2\/posts\/35333"}],"collection":[{"href":"https:\/\/www.uncommongoods.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.uncommongoods.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.uncommongoods.com\/blog\/wp-json\/wp\/v2\/users\/32"}],"replies":[{"embeddable":true,"href":"https:\/\/www.uncommongoods.com\/blog\/wp-json\/wp\/v2\/comments?post=35333"}],"version-history":[{"count":0,"href":"https:\/\/www.uncommongoods.com\/blog\/wp-json\/wp\/v2\/posts\/35333\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.uncommongoods.com\/blog\/wp-json\/wp\/v2\/media\/35353"}],"wp:attachment":[{"href":"https:\/\/www.uncommongoods.com\/blog\/wp-json\/wp\/v2\/media?parent=35333"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.uncommongoods.com\/blog\/wp-json\/wp\/v2\/categories?post=35333"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.uncommongoods.com\/blog\/wp-json\/wp\/v2\/tags?post=35333"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}