250/243

250/243 is known as the porcupine comma, maximal diesis or the chromium quartertone.

Interval information

Ratio	250/243
Factorization	2 × 3-5 × 53
Monzo	[1 -5 3⟩
Size in cents	49.16614¢
Names	porcupine comma, maximal diesis
Color name	y31, Triyo comma
FJS name	[math]\displaystyle{ \text{A1}^{5,5,5} }[/math]
Special properties	reduced
Tenney norm (log2 nd)	15.8906
Weil norm (log2 max(n, d))	15.9316
Wilson norm (sopfr(nd))	32
Comma size	medium
S-expression	S102⋅S11
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Theory

Measuring about 49 ¢, it is a medium comma. It is the amount by which two minor whole tones exceed a minor third, that is, (10/9)²/(6/5). Tempering it out leads to 5-limit porcupine temperament.

It serves as a period in the chromium temperament, where it is mapped to 1/24th of the octave.