Does 636 Million mean 636.000 million?

Yeah.

To a professional mathematician, engineer, scientist, or technologist there is definitely a difference in meaning between 636 million and 636.000 million : . the first is specified with an accuracy of 3 significant figures, and the second is specified with an accuracy of 6 significant figures.
. More precisely:

(a) 636 million = n₁ such that 635.5 x 10⁶ ≦ n₁ < 636.5 x 10⁶ and . (b) 636.000 million = n₂such that 635.9995 x 10⁶ ≦ n₂ < 636.0005 x 10⁶ . These are important distinctions between genuine differences in meaning that are relevant in such things as tolerance figures, that can have a bearing on the decision whether a mathematical calculation is acceptably accurate or totally meaningless and unreliable. .

– Best wishes - Majikthise. .

Yes it does

You are entitled to your opinion, even though it is wrong in the opinion of people who use mathematics professionally. I quote the following: “… Trailing zeros in a number containing a decimal point are significant. For example, 12.2300 has six significant digits: 1, 2, 2, 3, 0 and 0. The number 0.000122300 still has only six significant digits (the zeros before the 1 are not significant). In addition, 120.00 has five significant digits. This convention clarifies the precision of such numbers; for example, if a result accurate to four decimal places is given as 12.23 then it might be understood that only two decimal places of accuracy are available. Stating the result as 12.2300 makes clear that it is accurate to four decimal places. …” froim the wiki article at http://funadvice.com/r/bh42tv4n571

look at the maths professor lol