Abacus: Seven Digits, Two Versions, 90mm x 140mm, Chinese or Japanese, designed for easy assembly.
The abacus is an ancient calculator that comes in various styles, still used widely in Asian cultures as a way to help children build number sense or as a toy. It makes a nice-looking multi-wheeled toy car or a sound shaker like maracas!
The Chinese abacus has seven beads on a vertical bar, while the Japanese version has five beads on a vertical bar. As a general rule, each bead in the lower deck represents one when moved toward to center beam. Each bead in the upper deck represents five when moved to the center beam. On the Japanese abacus, each bar could represent zero to nine units. By contrast, the Chinese abacus allows the representation of zero through 15 units on each bar, thus supporting calculation using the base-16 system. For the base-10 system, the two beads at the very top and bottom are not used. About the decimal point, users could, in fact, choose their own place, depending on their specific needs. So as you can see, the abacus is a blend of concrete and abstract representations.
As always, small parts can be dangerous for small children; please educate young children not to put little parts in their mouth and follow all safety procedures when working with young children. Have fun making and playing on your abacus!
If you like Android apps, my Android app is at https://play.google.com/store/apps/details?id=appinventor.ai_moodle_bu.TouchAbacusforKids
- Dilson, Jesse. (1968). The abacus: The world’s first computing system: where it comes from, how it works, and how to use it to perform mathematical feats great and small. New York, NY: St. Martin’s Press.
If small parts have trouble staying on bed, please consider use a raft. In my experience, they are fine without a raft. I did have a few failures, tough.