Calculating Percent Lost

I'm embarrassed that I'm even asking this question...for real.

How do you calculate the percent weight that you've lost in a week? 

For example, let's say someone goes from 175 to 173.

Is it, 2/175 because he lost 2 pounds out of a starting 175, which gives a percentage of 1.1%?

I'm sitting here scratching my head and feeling really stupid - I can't believe I can't remember this simple bit of basic math!

Thanks!

Weight lost/sarting weight will give you percentage lost.  1.1% is right. 

Well.. I don't, usually, but..

% Lost = Poundage Lost / Original Poundage * 100

so... if you were 175 and are down to 173

(175-173) / 175 * 100 = 1.14%

Yep, thats pretty much it.

173 is 98.9% of 175  (173-175)

So you can either do 100%-98.9%  or the quick route of 2/175

Thank you!  :)