The metric system

I'll admit I haven't gotten used to the metric system.  The nutrition facts on packaged food are similar here, but the serving size is apparently (and sensibly) mandated;  It is always 100g.  This is a pretty inscrutable description for me though.  And it never tells you how many servings are in the package, forcing me to do math.

If you have trouble with the metric system too, xkcd can help.