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Galileo's Pendulum

## Equality, mathematical and practical

29 Mar 2013, 15:24 UTC
(200 words excerpt, click title or image to see full post)

No one can rival a beginning teacher for focusing on details at the expense of the big picture, much to the frequent chagrin of their students. One of my office mates in graduate school used to take points off of his students’ assignments if they wrote things like “2 π = 6.28″, since (as he [...]

Pi for equality.
No one can rival a beginning teacher for focusing on details at the expense of the big picture, much to the frequent chagrin of their students. One of my office mates in graduate school used to take points off of his students’ assignments if they wrote things like “2 π = 6.28″, since (as he said) that meant they were saying that π = 3.14 exactly. He wanted them to use the symbol for approximate equality, which is two wiggly lines: ≈.
Of course, as several of us pointed out to him, the students didn’t really mean that π = 3.14 to all levels of precision. They were using the equals sign in a common sense, as a way to assign a number to a symbol. The truth is that π is very close to 3.14 in value; if you leave ...