groove with a single bead. The columns are marked I for units, X for tens, C for hundreds, and so on up to millions.

In each column, the beads in the lower groove represent single units of that column's value, while the bead in the upper shorter groove represents five units. This arrangement resembles a bi-quinary coded decimal place-value system.

Fractional columns

The two rightmost columns were used for fractional counting. The column marked ? was used for counting

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