There is a prevailing stereotype that American blacks are not capable of simple arithmatic.
It is the nature of stereotypes that they are often accurate in describing 60 to 90% of the population being categorized. Sometimes stereotypes are positive other times, not so.
In my experience, with hundreds of close friendships with American blacks, the stereotype was disproportionately accurate.
I learned early on the job that black peers and audiences could not follow a numerical presentation. It would have been easy to manipulate this fact. I didn't. I found other ways to present the numeric data. Usually in the form of a story like the Uncle Remus stories.
I bring this up simply because it is unfortunate that we have a president who seems to have the black arithmatic failure implicit in this stereotype.
President Obama, has been corrected, but fails to understand simple numbers. He has been told many times that the upper most part of our taxpaying population pays a larger percent of their income in taxes than the middle class. He doesn't understand.