Mayan Abacus

[mcvoid]

Quick version: Do the rows and beads of a nepohualtzitzin directly correspond to the Mayan digits?

Long version: I'm working on a simulation of a nepohualtzitzin, which is a Mayan/Aztec abacus. I've been doing some independent research and learned the Mayan numerals and the base-20 system, and it seems to me that each row corresponds to a single numeral, and that the one's beads correspond to a dot, a five's bead is a line, and each row is a power of 20. Easy, right?

However, the material my client has provided insists that each row in the abacus is base-10, so that the beads and rows on the abacus don't match up with the numerals. Google isn't turning up anything useful in English to clarify, as most material is on its historical significance and relation to the calendar. This change is trivial for manual manipulation purposes, but it turns relatively simple logic into a nightmare when you take carrying and addition and multiplication into account. I need to know which is correct: my instinct or my documentation?

[nishank]

Can you give more details.
why is the client insisting on base 10

[mcvoid]

I'm not sure the client is aware for the problem yet, though I'm going to voice my observations at the next meeting. The material the client provided, which is in Spanish so I can't actually read it, is instructions aimed at kindergarden-level students. I suspect it was written for the purpose of teaching Mexican students how to use an abacus in base-10 while exposing them to some culture, glossing over the fact that the Maya used base-20.

Of course, it ultimately doesn't matter which way is "right": what the client wants is what they'll get regardless of authenticity, but I just want to confirm or debunk my suspicions for my own personal satisfaction.

[Tirian]

My understanding is that same as yours. The Mayans did their math in base-20 and the reason the nepohualtzintzin has three beads in the top segment of each rod is so they can count three groups of five before carrying. I appreciate the goals of multicultural education, but I would argue that confusing the nepohualtzintzin and the suanpan demeans both the Mayans and the Chinese.

[mcvoid]

I am of the same opinion. Thank you!