{"id":97,"date":"2010-07-13T16:19:39","date_gmt":"2010-07-13T16:19:39","guid":{"rendered":"http:\/\/mathriddles.williams.edu\/?p=97"},"modified":"2025-01-27T09:41:32","modified_gmt":"2025-01-27T14:41:32","slug":"legal-21-officer","status":"publish","type":"post","link":"https:\/\/sites.williams.edu\/mathriddles\/difficulty\/hard\/legal-21-officer\/","title":{"rendered":"Legal 21, Officer"},"content":{"rendered":"<p>Young Saul, a budding mathematician and printer, is making himself a fake ID. He needs it to say he&#8217;s 21. The problem is he&#8217;s not using a computer, but rather he has some symbols he&#8217;s bought from the store, and that&#8217;s it. He has one 1, one 5, one 6, one 7, and an unlimited supply of + &#8211; * \/ (the operations addition, subtraction, multiplication and division). Using each number exactly once (but you can use any number of +, any number of -, &#8230;) how can he get 21 from 1, 5, 6, 7?<\/p>\n<p>Note: you can&#8217;t do things like 15+6 = 21. You have to use the four operations as &#8216;binary&#8217; operations: ((1+5)*6)+7.<\/p>\n<p>Problem submitted by ohadbp@infolink.net.il, phrasing by yours truly.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Young Saul, a budding mathematician and printer, is making himself a fake ID. He needs it to say he&#8217;s 21. The problem is he&#8217;s not using a computer, but rather he has some symbols he&#8217;s bought from the store, and that&#8217;s it. He has one 1, one 5, one 6, one 7, and an unlimited&hellip;<\/p>\n","protected":false},"author":2861,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[11,12,14,6],"tags":[],"class_list":["post-97","post","type-post","status-publish","format-standard","hentry","category-algebra","category-combinatorics","category-general","category-hard"],"acf":[],"_links":{"self":[{"href":"https:\/\/sites.williams.edu\/mathriddles\/wp-json\/wp\/v2\/posts\/97","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/sites.williams.edu\/mathriddles\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/sites.williams.edu\/mathriddles\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/sites.williams.edu\/mathriddles\/wp-json\/wp\/v2\/users\/2861"}],"replies":[{"embeddable":true,"href":"https:\/\/sites.williams.edu\/mathriddles\/wp-json\/wp\/v2\/comments?post=97"}],"version-history":[{"count":1,"href":"https:\/\/sites.williams.edu\/mathriddles\/wp-json\/wp\/v2\/posts\/97\/revisions"}],"predecessor-version":[{"id":1173,"href":"https:\/\/sites.williams.edu\/mathriddles\/wp-json\/wp\/v2\/posts\/97\/revisions\/1173"}],"wp:attachment":[{"href":"https:\/\/sites.williams.edu\/mathriddles\/wp-json\/wp\/v2\/media?parent=97"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/sites.williams.edu\/mathriddles\/wp-json\/wp\/v2\/categories?post=97"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/sites.williams.edu\/mathriddles\/wp-json\/wp\/v2\/tags?post=97"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}