For example, ancient Mesoamerican civilizations common used vigesimal systems (base 20). In common with the other Mesoamerican civilizations, the Maya used a base 20 (vigesimal) system. Like all other languages of the Mesoamerican linguistic area, Otomi has a vigesimal number system. As mentioned, the Mesoamerican numbering system was vigesimal (i.e., based on the number 20). Classical Nahuatl has a vigesimal or base 20 number system. It was a vigesimal (base-20) positional numeral system. This inconsistency with its decimal system suggests that spoken Angkorian Khmer used a vigesimal system. The Mayas used a positional base-twenty (vigesimal) numerical system which only included whole numbers. Similar to other Celtic languages, Breton has an underlying vigesimal counting system. Inuit languages, like other language groups use a vigesimal, or base-20, counting system. Counting in Welsh combines the vigesimal system (counting in twenties) with some other features. A short count "tzolk'in" overlaps vigesimal named days with tridecimal numbered days. Ninths in vigesimal have six-digit periods. In these languages the systems are vigesimal up to 99, then decimal from 100 up. The vigesimal system remains in robust use.