<story><title>My bank sent me 64 copies of the same debit card</title><url>https://old.reddit.com/r/mildlyinteresting/comments/m2x83h/my_bank_sent_me_64_copies_of_the_same_debit_card/</url></story><parent_chain><item><author>mattl</author><text>A bank in Boston once sent me a debit card that didn&amp;#x27;t meet the valid number algorithm. I had to go in there and show them the math step by step to prove it.</text></item></parent_chain><comment><author>m463</author><text>I&amp;#x27;m surprised YOU even know.&lt;p&gt;meaning two things: you understand the algorithm &lt;i&gt;and&lt;/i&gt; you checked the algorithm.&lt;p&gt;This is like discovering a compiler bug from code that compiled - statistically unlikely, and requires deeper expertise.&lt;p&gt;I mean I shouldn&amp;#x27;t be surprised, it&amp;#x27;s HN.</text></comment>
<story><title>My bank sent me 64 copies of the same debit card</title><url>https://old.reddit.com/r/mildlyinteresting/comments/m2x83h/my_bank_sent_me_64_copies_of_the_same_debit_card/</url></story><parent_chain><item><author>mattl</author><text>A bank in Boston once sent me a debit card that didn&amp;#x27;t meet the valid number algorithm. I had to go in there and show them the math step by step to prove it.</text></item></parent_chain><comment><author>LeoPanthera</author><text>Why would you even try? Surely &amp;quot;my card number doesn&amp;#x27;t work&amp;quot; is the simple and sane response. They don&amp;#x27;t need to know, or care, &lt;i&gt;why&lt;/i&gt;.</text></comment>