Assertion: abacus | /r/HasProperty | modified
Facets:
Source sentences:
text: 19 X 1 (1st column) = 19 9 X 20 (2nd column) = 180 5 X 360 (3rd column) = 1800 Total: 1999 The abacus shown above has been modified to reflect the Calendric use of the Mesoamerican vigesimal number system.