As the first footnote explains, bi-quinary numbers are what an abacus uses: one part is 0,1,2,3 or 4 and the other is 0 or 5. Qui-binary numbers are the opposit

As the first footnote explains, bi-quinary numbers are what an abacus uses: one part is 0,1,2,3 or 4 and the other is 0 or 5. Qui-binary numbers are the opposite: one part is 0,2,4,6 or 8 and the other part is 0 or 1.