How many eggs are in seven dozen? If ten people walk nine miles in six hours, what was their average speed?
When people say, "Do the math," these days, they usually mean do the simple calculation needed to understand the situation. However, many people now lack the ability to do the math because they never learned the basic math facts or simple methods of calculation in school. What's worse, the school taught them to believe that making those simple calculations was not necessary. The result is that millions of people today lack the fundamental skills needed for productive lives. They believe it is their own fault for not having basic skills and fundamental knowledge. Many do not even know how little they know, because if they don't master the basics, many doors of learning are closed to them.
We often hear the phrase, "Do the math." Unfortunately for far too many of today's public school graduates, they can't.