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?
Where to get Yupana
The source code is available on the Sugar Labs Gitorious server.