Ah, the khipu. The way that it represents numeric info is somewhat well understood already:
- it's all base 10, positional. The tens/hundreds/etc. of different strings in the same khipu are aligned.
- zero = no knot
- 1~9 in the tens, hundreds etc. are represented by 1~9 simple knots
- 1 in the units is represented by a figure 8 knot
- 2~9 in the units is represented by a long knot with 2~9 turns
This might sound complicated but it's really elegant, and representing the units in a different way allow you to cram multiple numbers into the same string.
So for example. Let's say that you want to record 234 and 506 into a string. You'd do the following:
- 2 simple knots
- 3 simple knots
- long knot with 4 turns
- 5 simple knots
- space
- long knot with 6 turns
In some cases there might be geographical info in the khipu too, with numbers representing localities. Kind of like postal codes. The material of the string and the colour likely encode some info too, but AFAIK nobody knows it any more.
I'm almost sure that it doesn't contain any sort of textual info, though. Like, something you can read. Classical Quechua had at least 17 consonants, this would be impractical to represent through knots, specially as Quechua tends towards large words.
My bet on both "paired" khipukuna is that one encodes income, another outcome. Kind of like double bookkeeping but for material.