In a manner of speaking, I have been researching links between Music and Math (which shall be capitalised out of politeness) for my Extended Essay. Edging away from the Fourier series out of hearstopping awe for the power of said mathematics, I stumbled across the ratio of frequencies. And G-d said: "And thou shall create the notes in a geometric sequence. And the frequency of each note over the frequency of the preceeding note shall be equal to a constant, which shall be 2^(1/12)". And it was done. "And the frequency 440 shall be termed A". And it was done. "And two notes with the frequency ratio 3/2 when divided shall be named perfect fifths". And it was done. A and E are perfect fifths. A is 440. E is 659.25511382573985947168352209311. 659.25511382573985947168352209311/440 does not equal 3/2. It is a bit less. The proper perfect fifth of 440 A is 660. Why are A and E still perfect fifths?