Most G(r)eeks Know This

, , , , , | Learning | January 4, 2019

(My math teacher isn’t great. My two friends and I often sit off to the side of the class and do other homework while keeping an eye on her, because we are well ahead of this class and she is painfully slow in teaching the topics. On the bright side, she allows this because we do well in class. On the not-so-bright side, we’ve also had several disagreements with her about the accuracy of what she is teaching, most notably, her insistence that the constant pi is equal to 22/7 — not close to it, but equal to that exact value. In actuality, pi is not the same as any number, and famously requires lots of work to calculate ever more digits to be ever more precise. Most geeks know this, and all math teachers should. During two earlier incidents we’d given up trying to convince her she was wrong. On this particular day, she starts teaching the class about rational and irrational numbers. Rational numbers can be expressed by a ratio of integers — i.e. 22/7 — while irrational numbers cannot — i.e. pi. She starts putting down examples in two columns. As shown in the book, she puts pi in the irrational numbers category.)

Friend: “So… if pi is 22/7, that is a ratio of two integers. Why isn’t it listed as a rational number?”

(She looks flustered and thinks for a good thirty seconds, then erases pi and moves it to the rational numbers column.)

My Friends & Me: “Noooooo!”

(This suddenly became our Alamo, our line in the sand. We weren’t giving up this time. It took us another fifteen minutes of arguing to finally convince her that while pi was approximated as 22/7, this wasn’t its actual value. We had to dig through some extra textbooks she had in her cabinets to find an earlier textbook that stated this explicitly and simply in a single sentence in order to convince her, but she finally admitted she was wrong. The reason she had so many spare textbooks sitting in her cabinets? She was the head of the math department and they were samples from publishers. Also, this was the honors class.)

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