Urton speculates that these sums might record tax payments. Incans paid their taxes by working a certain number of days per year on state projects. The knotted strings could represent such days, and the sums could represent totals for all work in a certain area, Urton says.
I find that interesting that rather than pay tax, you work on some state projects. Hmm, given the choice, I might rather do that. People take pride in their handiwork, would all of us be more considerate of our public places if we contributed to them personally? I guess if it were a matter of choice, pay or work, it would depend on the work. I wouldn't mind working on a community project of beautification or some such and keep more of the money I earn, but then I wouldn't be earning any money if I were off on a project! I found it interesting, and could a version of this work in a capitalistic society?
In any event, the knots were cool.