Abacus (8 h 3 m, 6 ago 1300 ano – 6 h 48 m, 30 nov 1300 ano)

Descrição:

It was a counting frame that they used in Europe . It was created in 500 B.C. but wasn't used till 1300 A.D. Image: https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&ved=0ahUKEwiuro6KrfjWAhXFy4MKHT77AvsQjRwIBw&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FAbacus&psig=AOvVaw3wknx-Z7o60cKC8nn8QKjC&ust=1508353571396909

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