AMU So... I'm wondering what the measurement of an AMU (atomic mass unit) is... I mean.. I've heard it's really the weight of a proton but then I'm told the proton's weight is actually 1.0073 amu.. so what is the amu based on then? btw: how do you pronounce a decimal number such as ... .0007 or .0000009? Thanks. ALSO... I was reviewing diff temp conversion and the "formulas" for them... I noticed something that kind of made me stop for a second... (F - 32ºF) x (5ºC/9ºF) = C Now.. knowing how both temps are the same at -40º, I worked it out and it doesnt quite work when it's done like this: -40 - 32 = -72 now take 5/9 = .555555etc... that means it cant possibly be -40 but instead around 39.999 or something... Now.. if you instead cross multiple and simplify the 72 into an 8 and the 9 into a 1 then you get: -8 x 5/1 = -40 My problem clearly is mathematical... so I'm wondering what I'm doing wrong.. and why with the two "valid" methods there is a difference, small but there's one. I hope it's not some theory of how .999999999999999999999 is technically one.