How can one tell if a business is working?

Perhaps the best way to tell whether a business is
"working" (whether it is doing well) is by looking at the profit margin of the
business.

In order to find the profit margin of a business,
you must first subtract total costs from total revenues over some defined period.  You
then take that number (which is your profit) and divide it by the total revenues.  This
tells you more than you would get simply by looking at total profit.  That is because
profit margin tells you how efficient the company is.  It tells you how much profit you
are making for every dollar of product that you
sell.

Profit margin, then, can tell how efficiently your
business is working as well as how much money it is making.  This makes it a good
measure of the firm's health.