- Undecimal
The undecimal (base-num|11)
positional notation system is based on the number eleven, rather than ten as indecimal or eight inoctal and so on. It is not a commonly used system. Undecimal requires eleven symbols representing the decimal numbers 0 through 10. For example, if the symbol for 10 were 'A', the decimal numbers 0 to 24 in undecimal would be: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 1A, 20, 21, 22. The undecimal number 1A3 would be 234 in decimal.Base 11 in Fiction
Base 11 systems appear in several
science fiction stories:Carl Sagan 's novel Contact references a message "hidden" insidepi that is most striking in base 11, as that permits it to be displayed inbinary code . Also the fictionalPsychlo s ( inL. Ron Hubbard 's bookBattlefield Earth ) have a base-11 counting system.In the show
Babylon 5 , theMinbari use Base-11 mathematics, according to the show's creator.ISBN Check Digit
The check digit for
ISBN is found as the result of taking modulo 11. Since this could give 11 possible results, the digit "X" is used in place of "10".External links
* [http://www.intuitor.com/counting/ Learn to count other bases on your fingers]
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