The earliest reference of a number system I could find goes back 1,300 years, but I&#x27;d be completely surprised if the basic concepts weren&#x27;t much older.<p><a href="http:&#x2F;&#x2F;mt.artofmemory.com&#x2F;wiki&#x2F;Major_System#History" rel="nofollow">http:&#x2F;&#x2F;mt.artofmemory.com&#x2F;wiki&#x2F;Major_System#History</a><p>Example: in Greek and Hebrew, numbers were already mapped to letters, so it would be very small step to create mnemonics from the numbers based on the letters.<p><a href="http:&#x2F;&#x2F;www-history.mcs.st-and.ac.uk&#x2F;HistTopics&#x2F;Greek_numbers.html" rel="nofollow">http:&#x2F;&#x2F;www-history.mcs.st-and.ac.uk&#x2F;HistTopics&#x2F;Greek_numbers...</a><p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Hebrew_numerals#Main_table" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Hebrew_numerals#Main_table</a>