X Vs. *

[Boerseun]

So... stoopid question time:

 

On all the computers I have ever owned, worked on, looked at, seen, you name it, the math operators on the keyboard are plus (+), minus (-), divide (/) and multiply (*).

Yet, on all the calculators I have ever had or seen, the divide sign is a minus with a dot above and a dot below (can't type it 'cause I don't have that particular character on my keyboard - it's prolly somewhere in the ASCII map) and the multiply sign is an x. So why did they change the x into an asterisk when it came to computing? And why do we have to use the slash "/" for divide, instead of the proper division symbol that appears on calculators?

 

Me not understand. I'm sure there's a very good reason for it. If you know, please enlighten me.

[CraigD]

So why did they change the x into an asterisk when it came to computing? And why do we have to use the slash "/" for divide, instead of the proper division symbol that appears on calculators?

 

Me not understand. I'm sure there's a very good reason for it. If you know, please enlighten me.

I’m not quite old enough to have “been there” when these conventions were adopted, but having used with them nearly every day for the past 35 years, I think I’ve a pretty good opinion about the why of it.

 

“X” was replace by “*” as the multiplication symbol to avoid ambiguity in math expressions such as [math]x \times y + z[/math] or [math]xy + z[/math], x and alphabetic character strings containing x being a popular variable names. “*” resembles another popular multiplication symbol, [math]\cdot[/math], making it an obvious choice for an unambiguous multiplication symbol.

 

“[math]\div[/math]” was replaced by “/” as the division symbol because the first popular standard character sets, in particular the 95 printable ASCII characters, had not too many special punctuation characters, and simply didn’t include “[math]\div[/math]”. “/” resembles the line separating numerator and denominator in the usual math fraction notation (eg: a/b resembles [math]\frac{a}{b}[/math]), making it an obvious choice.

 

Extended character coding schemes (eg: ISO 8859) provided 8-bit (vs ASCII’s 7-bit) characters including [math]\times[/math] and [math]\div[/math], but were only widely adopted by the mid 1980s, decades after * and / were well-entrenched in computer coding convention and typewriter-style keyboard standards.

 

Electronic and mechanical calculators, having specialized keyboards and printing/display devices, following fewer standards than typewriter keyboards and printing/display devices, were not so constrained, so usually have the older [math]\times[/math] and [math]\div[/math] multiplication and division symbols.