When is 15 pronounced "FIF-teen", and when is it pronounced "fif-TEEN"? I'm a mathematician, and my wife teaches English as a Second Language, so you'd think we'd know the answer to this one, but the tacit rules followed by American speakers seem to be a bit complicated. When counting from one to twenty, we say "FIF-teen". When it's quarter past the hour and we're telling someone the time in hours and minutes, we say "fif-TEEN". When talking about a year in the 1500's, we say "FIF-teen". When talking about a young person's age, we say "fif-TEEN". When talking about how many dollars something costs, the two syllables get almost equal stress, but the first syllable gets slightly more. Do you folks agree with these examples? Is there a general rule lurking here for numbers between 12 and 20? Jim