{"id":5237,"date":"2012-10-21T18:19:35","date_gmt":"2012-10-21T18:19:35","guid":{"rendered":"https:\/\/noi3.org\/site\/?p=5237"},"modified":"2012-10-21T18:19:35","modified_gmt":"2012-10-21T18:19:35","slug":"credit-card-numbers-are-not-random-how-to-read-understand-them-yourself","status":"publish","type":"post","link":"https:\/\/site.noi3.org\/?p=5237","title":{"rendered":"Credit Card Numbers Are Not Random: How To Read &#038; Understand Them Yourself"},"content":{"rendered":"<header style=\"padding:0;\">\n<p> \t\t&nbsp;<\/p>\n<\/header>\n<p> \t<img decoding=\"async\" alt=\"understand credit card numbers\" class=\"align-right\" src=\"http:\/\/main.makeuseoflimited.netdna-cdn.com\/wp-content\/uploads\/2012\/10\/shutterstock_108735110_credit_card_300.jpg?6cc8a5\" style=\"height: 250px; width: 250px;\" \/>You may have heard before that credit card numbers follow a certain pattern and structure so that they can be validated before a transaction is accepted. However, it&rsquo;s one thing to know that the structure is there and another thing entirely to understand how credit card numbers work.<\/p>\n<p> \tWhy would this knowledge be useful? Well, if you run a small business that doesn&rsquo;t process credit card payments immediately, you could save yourself money by ensuring the card details are valid. If you don&rsquo;t, well it could still be fun to show off your skills at parties. Here&rsquo;s how you do it.<\/p>\n<p>  <!--more-->  <\/p>\n<p> \t&nbsp;<\/p>\n<p> \t<img decoding=\"async\" alt=\"understand credit card numbers\" class=\"align-right\" src=\"http:\/\/main.makeuseoflimited.netdna-cdn.com\/wp-content\/uploads\/2012\/10\/shutterstock_108735110_credit_card_300.jpg?6cc8a5\" \/>{{all}}<\/p>\n<p> \tYou may have heard before that credit card numbers follow a certain pattern and structure so that they can be validated before a transaction is accepted. However, it&rsquo;s one thing to know that the structure is there and another thing entirely to understand how credit card numbers work.<\/p>\n<p> \tWhy would this knowledge be useful? Well, if you run a small business that doesn&rsquo;t process credit card payments immediately, you could save yourself money by ensuring the card details are valid. If you don&rsquo;t, well it could still be fun to show off your skills at parties. Here&rsquo;s how you do it.<\/p>\n<h2> \tLearning Where The Numbers Come From<\/h2>\n<p> \tCredit card numbers are not random. There&rsquo;s a special set of numbers to show information about the card issuer and another set to show information about the card holder. One other number is also important, but we&rsquo;ll come to that later.<\/p>\n<p> \t<strong>The very first number is the Major Industry Identifier (MII)<\/strong> and it tells you what sort of institution issued the card.<\/p>\n<ul>\n<li> \t\t1 and 2 are issued by airlines.<\/li>\n<li> \t\t3 is issued by travel and entertainment.<\/li>\n<li> \t\t4 and 5 are issued by banking and financial institutions.<\/li>\n<li> \t\t6 is issued by merchandising and banking.<\/li>\n<li> \t\t7 is issued by petroleum companies.<\/li>\n<li> \t\t8 is issued by telecommunications companies.<\/li>\n<li> \t\t9 is issued by national assignment.<\/li>\n<\/ul>\n<p> \t<strong>The first six digits are the Issuer Identification Number (IIN)<\/strong>. These can be used to look up where the card originated from. If you have access to a list that details who owns each IIN, such as this <a href=\"http:\/\/en.wikipedia.org\/wiki\/List_of_Issuer_Identification_Numbers\">list of popular IINs<\/a> on Wikipedia, you can see who issued the card just by reading the card number.<\/p>\n<div id=\"muo_ad_middle\" style=\"line-height: 16px;\"> \t&nbsp;<\/div>\n<p> \tHere&rsquo;s a few you might recognise:<\/p>\n<ul>\n<li> \t\tVisa: 4*****<\/li>\n<li> \t\tAmerican Express (AMEX): 34**** or 37****<\/li>\n<li> \t\tDiner&rsquo;s Club International: 36****<\/li>\n<li> \t\tMastercard: 51**** to 55****<\/li>\n<\/ul>\n<p> \t<strong>The seventh digit to the second-to-last digit is the customer account number<\/strong>. Most companies use just 9 digits for the account numbers, but it&rsquo;s possible to use up to 12. This means that using the current algorithm for credit cards, the world can issue about a trillion cards before needing to change the system.<\/p>\n<p> \t<img decoding=\"async\" alt=\"understand credit card numbers\" class=\"aligncenter\" src=\"http:\/\/main.makeuseoflimited.netdna-cdn.com\/wp-content\/uploads\/2012\/10\/shutterstock_111048326_credit_card.jpg?6cc8a5\" \/>{{all}}<\/p>\n<p> \tWe often see 16-digit credit card numbers today, but it&rsquo;s possible for a card issuer to issue a card with up to 19 digits using the current system. In the future, we may see longer numbers becoming more common.<\/p>\n<p> \t<strong>The very last digit of each credit card is the check digit, or checksum<\/strong>. It is used to validate the credit card number using the Luhn algorithm, which we will now explain in detail.<\/p>\n<h2> \tThe Luhn Algorithm Validation Check<\/h2>\n<p> \tThe <a href=\"http:\/\/en.wikipedia.org\/wiki\/Luhn_algorithm\">Luhn Algorithm<\/a> is used to validate all sorts of numbers, including credit cards, IMEI numbers and some social security numbers. It&rsquo;s not designed to be a cryptographically secure hash function, but merely a way to check errors are not made when recording numbers. It is not foolproof, but is generally considered to be useful.<\/p>\n<p> \tTake the credit card number and read the digits from the right. Double every other number and write them down &ndash; if you do it in the same order as your card is written it will help with clarity. Now, wherever you have calculated a double-digit number, change it so that it reads as &ldquo;first digit + second digit&rdquo; (in other words, sum the digits of the products). Finally, take your calculations and add those numbers to the numbers remaining on your card that you didn&rsquo;t double. A legitimate credit card number will give you a result that is divisible by 10.<\/p>\n<p> \tFor instance, let&rsquo;s use a number I&rsquo;ve just made up: 4634 8932 1298 2767. I&rsquo;ll enter it into a table to make it easier to understand the steps.<\/p>\n<p> \t<img decoding=\"async\" alt=\"understand credit card numbers\" class=\"aligncenter\" src=\"http:\/\/main.makeuseoflimited.netdna-cdn.com\/wp-content\/uploads\/2012\/10\/credit-card.png?6cc8a5\" \/><\/p>\n<p> \tTry it yourself using the card from the picture earlier in this article. What can you learn from it?Ar<\/p>\n<hr \/>\n<p> \t<a href=\"http:\/\/www.makeuseof.com\/tag\/credit-card-numbers-random-read-understand\/\">Articolul original<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>&nbsp; You may have heard before that credit card numbers follow a certain pattern and structure so that they can be validated before a transaction&hellip;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[31],"tags":[1017,1020,802,1018,1019],"class_list":["post-5237","post","type-post","status-publish","format-standard","hentry","category-altele-continut","tag-card","tag-credit","tag-explicatii","tag-numere","tag-semnificatie"],"_links":{"self":[{"href":"https:\/\/site.noi3.org\/index.php?rest_route=\/wp\/v2\/posts\/5237","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/site.noi3.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/site.noi3.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/site.noi3.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/site.noi3.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=5237"}],"version-history":[{"count":0,"href":"https:\/\/site.noi3.org\/index.php?rest_route=\/wp\/v2\/posts\/5237\/revisions"}],"wp:attachment":[{"href":"https:\/\/site.noi3.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=5237"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/site.noi3.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5237"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/site.noi3.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5237"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}