D'ni numerals

Note: Fictional details from the Myst franchise follow, and will be treated as facts.

D'ni numerals were the base-25 counting system used by the D'ni, as seen in the two computer games Riven and , and in Cyan's Myst novels.

Warning: Plot details follow.

It is suggested that you do not read this article or look at the accompanying picture until you have finished the game Riven. A significant part of the Riven end game is left inaccessible until the player has deduced the meaning of the symbols as numerals, and their values. The numerals also make a cameo appearance in . Finally, the meanings of numerals one through eight are presented much more straightforwardly in the Relto Age in .

Description

Though it is a base-25 numeral system, all numerals are derived from 5 basic glyphs. These glyphs unaltered are the "basic" numerals 0, 1, 2, 3, and 4. The numerals 1, 2, 3, and 4 are rotated ninety degrees counterclockwise to yield the "rotated" numerals 5, 10, 15, and 20, respectively. (Rotating the basic numeral, therefore, multiplies its value by five; this principle of Fives misleads many to believe that D'ni numerals are base-5.)

To yield the remaining digits 0 to 24, a basic numeral is superimposed upon a rotated numeral, adding the two values together. For example, a 4 is superimposed upon a 15 (a rotated 3) to yield the numeral for 19.

Having now derived digits for ALL numbers 0 to 24, higher numbers are derived as in any other place-value system. Digits are appended to the left, each representing a higher power of 25, with the zero numeral acting as placeholder.

There are two additional numerals, which are cultural symbols more than bona fide members of the D'ni numeral system.

The first is a single-digit 25 (an 'X'-shaped glyph). The D'ni used numbers to show degrees of extent or completeness (much as we use percentages). 25 represented utter completeness or the greatest possible extent. For instance, then, if a D'ni were extremely lonely, he might say he was "lonely to 25."

The other is a "cyclical zero" (a forward slash-shaped glyph). It was used in circumstances where numbers progress in a cycle, with the beginning tied to the end. Their clocks, for example, divided D'ni "minutes" into 25 D'ni "seconds." The first "second" of a "minute" was represented not by a typical 0 or 25, but by the cyclical zero, representing both the end of one "minute" and the beginning of another.

Overview graphic

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D'ni numerals overview (courtesy of Garternay.com)

• Fan's explanation of D'ni letters and D'ni numerals
• A more detailed look, by a fan