It has long been a mystery of Aztec arithmetic: What is three arms plus five bones? Now researchers know: Five hearts. The odd symbols had been noted for centuries; thousands of them appear in Aztec ...

It has long been a mystery of Aztec arithmetic: What is three arms plus five bones? Now researchers know: five hearts. The odd symbols had been noted for centuries -- thousands of them appear in Aztec ...

Long known for their cool circular calendars and practice of human sacrifice, Aztecs were also math whizzes. Subscribe to read this story ad-free Get unlimited access to ad-free articles and exclusive ...