octodecimal

English

Adjective

octodecimal (not comparable)

1. (crystals) Having eight times ten faces.
2. (arithmetic) Using eighteen as the base.

   Octodecimal 1249 is equivalent to decimal 6561 or nonary 10000.

   • 1907, The Dial - Volume 43, page 411:

     The decimal scheme should have been made a duodecimal, or better a quinquedecimal or octodecimal one; the expansive system would need a more than India-rubber elasticity to include all the whimsical creations of an author's brain.

   • 2012 January, Debasis Das, U.A. Lanjewar, “Realistic Approach of Strange Number System from Unodecimal to Vigesimal”, in International Journal of Computer Science and Telecommunications, volume 3, number 1:

     By studying other number system such as unodecimal (base-11), duodecimal (base-12), tridecimal (base-13), quadrodecimal (base-14), pentadecimal (base-15), heptadecimal (base-17), octodecimal (base-18), nonadecimal (base-19) and vigesimal (base-20), researcher will gain a better understanding of how number systems work in general.

   • 2013 May, “Subtraction in Traditional and Strange Number System by r's and r-1's Compliments”, in International Journal of Computer Applications, volume 70, number 23:

     Traditional number system — binary, octal, decimal and hexadecimal, in regular use and Strange number system, with an extra edge of memorized information with greater density, zero redundancy problem, avoiding sign problem and reducing complexity of interconnections, - unodecimal, duodecimal, tridecimal, quadrodecimal, pentadecimal, heptadecimal, octodecimal, nona decimal, vigesimal and further are discussed through compliments.

3. Pertaining to eighteen.
   • 1879, The Messenger of Mathematics, page 7:

     I say very considerably greater than, because only a certain number of the terms which satisfy the required conditions of order and weight actually appear in the octodecimal invariant in question.

   • 1950, Ramananda Chatterjee, The Modern Review - Volume 87, page 404:

     18 modes of archery and use of other implements of war (Adavuyal and Ayudhet prayogangal), 18 kinds of manners and customs (Nattacharangal) and there seems to be something of importance in this octodecimal division.

   • 1951, Inter-African Bureau for Soils and Rural Economy, African Soils - Volumes 1-3, page 107:

     it is reasonable to suppose that a warmer temperature will be manifest as from the octodecimal apex 1957-58, and will subsequently continue.

   • 1973, James Joseph Sylvester, 1854-1973, page 387:

     Of course all symmetrical invariants have an invariable sign ; but this is not the case with skew invariants, as for example, M. Hermite's octodecimal invariant of a binary quintic, which will change its sign with that of the determinant of transformation.

   • 2012, James Joseph Sylvester, H. F. Baker, The Collected Mathematical Papers of James Joseph Sylvester:

     But this magnificent discovery, whereby the determination of the number of fundamental invariants to a binary quantic of a given degree is reduced to a problem in the partition of numbers, it is but justice to M. Hermite to state, took its rise in that great analyst's discovery of the octodecimal invariant of the binary quintic.