Yupana is an Incan counting device similar to an abacus.
How to use the Yupana
The beads are organized in columns, where the units (1s) column is farthest to the right; tens (10s) is second from the right; hundreds (100s) is third from the right, etc.
Click on a dot and it will reverse its state (color), and either add or substract value from that column.
More details regarding the history and use of the Yupana can be found here:
- Did you know that you can use the yupana over the network with your friends?
An alternative interpretation
There are some alternative interpretations of how the Yupana works, e.g., . In this version, the base is 20, and rows with multiple dots are counted as 2s.
Yet another interpretation (by the author) is that the factor of each bead is based on the number of beads in its containing box, e.g., each bead in the top row, x1; in the second row, x2; in the third row, x3; and in the bottom row, x5.
Both of these alternative interpretations are available under the "spanner" toolbar beginning with Version 3.
As of Version 4, the learner can explore their own interpretations of how the Yupana works.
In the above example, the beads are valued as x1, x2, x6, and x24 with a base of 144. This is arguably the most efficient representation.
Where to get Yupana
The source code is available on the Sugar Labs Gitorious server.