Punkfolkrocker

Yes, music is VERY much based on maths and physics - did you see the reference to Pythagoras above? One of the foremost mathematicians of
classical times.

It was he who showed that the interval of a fifth was based on a 3/2 relationship.

Oh yes, my reference to 'natural' above was meant to refer to perfect 5ths - sorry if it is out of line with common usage.

I agree that even-tempered tuning is a compromise necessary for western music. It involves making each interval correspond to a multiple which is the 12th root of 2, so that multiplying by it 12 times brings you to a note of double the one you started with, i.e. a perfect octave.

According to Excel, this should be 1.059463094

Multiplying A=440 by this 7 times gives a fifth, the actual value of which will be 659.2551138

A perfect 5th would be 3/2 times 440, which is 660, therefore the even-tempered note is 0.74 too flat

If you could play the two together, you may hear a 'beat note' of the difference - like the ones Guitarists use when tuning.