Septimal kleisma

In music, the ratio 225/224 is called the septimal kleisma (play^ⓘ). It is a minute comma type interval of approximately 7.7 cents. Factoring it into primes gives 2⁻⁵ 3² 5² 7⁻¹, which can be rewritten 2⁻¹ (5/4)² (9/7). That says that it is the amount that two major thirds of 5/4 and a septimal major third, or supermajor third, of 9/7 exceeds the octave.

Septimal kleisma: B♯

The septimal kleisma can also be viewed as the difference between the diatonic semitone (16:15) and the septimal diatonic semitone (15:14).