George Hammond writes:

On Tue, 29 Apr 2008 05:15:38 +0000 (UTC),
(Michael Moroney) wrote:


If a physicist making measurements writes down the following figures as
lab measurements, how many significant figures are in each number, and
why?

120
[GH] 2 significant figures
120.
[GH] 2 significant figures

If you were familiar with conventions with significant figures, you'd know
that if the zero in the units portion is significant (and there is no
fractional portion), you add a decimal point, otherwise you don't. The
correct answers are therefore 2 and 3 respectively.
Of course this is better resolved by using scientific notation.

469.230
[GH] 5 significant figures

6. There is no reason to write the zero unless it was significant. If
that number was measured to 5 sig figs, it should be written as 469.23 .

Since you didn't answer the question about showing how 12=13 to 3
significant figures (as you claim), your overall grade is really 5 out of
8, or 62.5%, which is an F. I'm being generous since you didn't answer any
of the "why" for the first seven questions. Please turn in your degrees to
the institutions that mistakenly awarded them to you.