D'ni numerals
D'ni numerals were the
base-25 counting system used by the
D'ni, as seen in several of the
computer games in the
Myst franchise, particularly in
Riven and , and also in
Cyan's Myst novels.
A significant part of the Riven endgame is inaccessible until the player has deduced the meaning of the symbols as numerals and deciphered their values. The player learns the D'ni numerals in
Riven by playing the game in the school where the prisoner is moved a certain number of clicks toward the whale-like creature depending on the number indicated on the spinning dial. Knowing the D'ni numerals is critical to finding the
Moiety Age.
The meanings of numerals one through eight are presented much more straightforwardly in the
Relto Age in
. The numerals also appear in the games
Myst III: Exile and
Myst V: End of Ages, although learning them is not necessary to complete those games.
Though it is a base-25 numeral system, all numerals are derived from five 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.
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." This use of 25, along with 25's general ubiquity in D'ni culture, made it expedient to have a single-character representation of the number.
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. (The idea came from a buggy single-digit 25 in the D'ni font Cyan used in Riven; the "cyclical" explanation was posited after the game's release, and was adopted by Cyan thereafter.)
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A more detailed look, by a fan
