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For PC calculators you use * instead of x, or / instead of ÷. Why were these two symbols chosen over the other two?

In the standard Windows calculator, even the button uses "/" instead of "÷"

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Because x is often the name of a variable, so using * for multiplication prevents confusion, and we don't want to introduce new keys to have a new key, $\times$, when we already have *. Similar with /. – Arturo Magidin May 23 '11 at 19:45
@Atruro I run calc.exe and I can't create variables. – Chris S May 23 '11 at 20:00
It doesn't matter; the point is that in early computer programming, x was a character, not a mathematical operator, and it's a character that is too easy to confuse with the mathematical symbol $\times$. You want a symbol which is easy to differentiate (for debugging purposes) and unambiguous, so the closely related * was chosen to denote multiplication. Neither $\times$ nor $\div$ were standard keys in standard typewriters, which made them difficult to add to early computing (typewriters used x). It keeps going from there. Do you have a $\div$ key on your keyboard? I don't. – Arturo Magidin May 23 '11 at 20:06
@Arturo I thought it may have an interesting mathematical reason but it's just the boring old restrictions of ascii – Chris S May 24 '11 at 8:52
up vote 2 down vote accepted

I don't know which came first in this case, but I'd have to believe it came from using $\cdot$ for multiplication in writing and $/$ came from the fraction symbol.

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I'd have to comment... – The Chaz 2.0 May 23 '11 at 20:05
@The Chaz: But I can't for lack of stupid rep! – t.b. May 23 '11 at 21:40
@Theo: Do you have a website or links to any projects you've worked on? (I understand if you prefer privacy) – The Chaz 2.0 May 24 '11 at 1:42
@The Chaz: I wouldn't use my real name if privacy was my concern here. Googling my name should bring up my old and neglected homepage in Göttingen with some texts I wrote some time ago. But be aware that I'm neither this guy nor that guy. Currently I'm at ETH Zürich. – t.b. May 24 '11 at 8:09

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