TETRACTYC ARITHMETIC, is that wherein only the Figures 1, 2, 3, and 0, are used.

We have a Treatise of this Arithmetic, by Erhard Weigel: But both Binary and this are little better than Curiosities, especially with regard to Practice; inasmuch, as the Numbers may be much more compendiously expressed by Decadal Arithmetic, than by either of them.