Unlike a digital computer, the brain does not use binary logic or binary addressable memory, and it does not perform binary arithmetic.

His latest installment is an article describing the strange implementation of the IBM 1401’s qui-binary arithmetic.

Leibniz developed this system to express numbers and all operations of arithmetic—addition, subtraction, multiplication, and division—in the binary language of 1s and 0s.

This is simple binary arithmetic. What happens when 10111 (+seven) and 11010 (+ten) are added together. The answer, obviously is seventeen. How is this represented in the five bit number format?

This article was originally published with the title “Experiments in Binary Arithmetic” inSA Supplements Vol. 17 No. 421supp(January 1884), p. 6726doi:10.1038/scientificamerican01261884-6726asupp ...

It seems that inhabitants of Mangareva island in French Polynesia created their own particular hybrid of decimal and binary number systems to do mental arithmetic.