According to Wikipedia, the size of the perfect fifth in 1/4 comma meantone is "flattened by one quarter of a syntonic comma, with respect to its just intonation used in Pythagorean tuning (frequency ratio 3:2)." How exactly is this done mathematically?
A pythagorean fifth is the ratio 3/2.
A fifth in 1/4 comma meantone is 5^1/4 (1.495).
The syntonic comma is 81/80.
When I try to calculate the size of the fifth I end up with 1.246875 instead of the expected 1.495. Here's how I'm getting there: subtracting (81/80 * 1/4) (a quarter of the syntonic comma) from a pure fifth (3/2). What am I doing wrong?