Calculated as the 9th root of 2 -- 9√2, or 2(1/9) -- an irrational proportion with the approximate ratio of 1 : 1.080059739, and an interval size of exactly 133 1/3 cents. It is the size of 1 degree in the 9-edo (or 9-tET) scale, 2 degrees of 18-edo, 4 degrees of 36-edo, and 8 degrees of 72-edo.
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