# How Did She Graduate From High School?

In the last days of my tenure and a couple weeks before my retirement in Spring 2014, as the final exams were approaching, one of my students visited me in my office with a question about a problem we had done in class. The problem was this: If a machine can toss a coin 100,000 times per second and you want it to toss the coin 2.2×1019 times, how many seconds do you have to wait? She didn’t understand why we had divided 2.2×1019 by 100,000 to get the answer. In such cases, I tell my students to replace the large numbers by small ones, because the power of ten may be too abstract for them. I asked her, “if you can toss a coin two times per second, how many seconds does it take you to toss it ten times?” She said, “two divided by ten?” … Because of grade inflation – which is out of my or any concerned teacher’s control – she got a B in my course! (If I hadn’t inflated the grades, I would have had to fail at least 70% of the class, including this girl who was better than the bottom half of the class!) This is a general-education course, whose prerequisite is the admission requirement to an American public university, i.e., allegedly high school algebra!