The smallest unit of measurement is 1/16 of an inch. When you look at a ruler and count all the lines between the 1 inch and 2 inch marks you will see that there are 16 lines all together.
A single serving of pasta is generally regarded as 2 oz. (57 g) of cooked pasta for a first course or side dish. A serving can be raised 3 to 4 oz. (85 to 113 g) if it is the only course. Occasionally a serving is approximated as 1/2 cup (114 g) of pasta; however, this depends upon the shape of the pasta.
Dry pasta is sold by weight, but that measurement doesn't tell you how much cooked pasta you'll actually end up with. Here's a handy guide to estimating how much dry pasta you'll need to make one serving of cooked. All of these estimates are based on a 2-ounce serving of dry pasta.