Multiplication sign, using '*' or 'x'

In mathematics, the operators provided on keyboard are quite clear for addition, subtraction and divide: + - /.

The multiplication sign * might be familiar as the multiplication for programmer, but I'm not sure about ordinary user. I don't know if I should use * or x for multiplication.

The purpose is to provide user detail of how each field will be used: One drawback I can think of is if using x might rely on font face and if user changes the font, x might not be appear like multiplication sign.

Also, by the standard * (asterisk) should be used to multiplication, but I'm not sure about its readability.

• I always had the impression that "*" was used as a multiplication operator because "•", commonly used in algebra, was hard to find on older (particularly PC) keyboard layouts, but looked similar enough to be interchanged. I am not confident that * is a good multiplication operator for human consumption. – msanford Nov 15 '11 at 21:11
• Please don't expect users to actually calculate the rates themselves! (Room Price + Charge) x Net Rate %, ... – Wousser Nov 16 '11 at 7:50
• @Wousser That is just a description of how each Apply Type will be used to calculate. The program will do it. – Sarawut Positwinyu Nov 16 '11 at 11:21
• Why not use ×? – hippietrail Nov 18 '11 at 14:51
• @hippietrail at the time i was writing this question. i didn't know that sign existed :) Thanks – Sarawut Positwinyu Nov 20 '11 at 5:07

It would certainly be a mistake to use the letter x as the multiplication symbol as x itself often denotes an algebraic term:

e.g. compare

x x y = c
x x y = c

vs

x × y = c
x × y = c

The &times; or &#215; or &#D7; character looks like this: × so it is a proper cross, as opposed to the letter x (ex) or * (asterisk) symbols which are a lazy approach and don't create symmetrical symbols about the major axes.

The &times; version is simply the friendly version of the same code.

For additional reference, for divide you can also use &divide; or &#247; to get ÷

For minus you might expect to use direct from the normal key, but there is a separate code for that too &#8722; − which aligns it vertically with the keyboard plus symbol, so you get ( −+ −+ ) instead of the keyboard minus and plus, which may not be aligned depending on the font ( -+ -+ ).

You can get the plus/minus via &plusmn; or &#177; ± .

There is another Wikipedia entry for the symbol itself, which currently consists of the information below:

(sorry, this is an image - so links are not real!) • Would be kind of nice if those were the symbols you got when using the keys on the numpad. – Svish Nov 15 '11 at 12:18
• @Svish You mean pressing '/' would give you ÷ and pressing '*' would give you ×? – Kris Harper Nov 15 '11 at 15:06
• There is a semantic difference for multiplication on non-scalars. For vectors A × B (cross product) is not the same as A ∗ B (dot product). – zzzzBov Nov 15 '11 at 15:33
• Ah, I never knew there was a Unicode for either the '×' OR '÷' symbol. (Well, TBH i've never really looked). Now I know. – JonW Nov 15 '11 at 15:37
• also, don't forget to use &lowast; (∗) instead of an asterisk (*) – zzzzBov Nov 15 '11 at 15:38

It's a shame that I found the solution after posting my own question. So I will just share it there. Wikipedia recommends using The HTML entity &times; which will be resulted in × for multiplication:

Multiplication

List_of_XML_and_HTML_character_entity_references

In addition to all of the other pro voices for *, the numeric keypad on my keyboard has a * for times. That's another argument, IMO, for using it.

• Absolutely not from a UI point of view. That is only an argument as to why it is easier, not as to why it is better. – Paul Wagland Nov 17 '11 at 17:38
• +1 because, as my answer gets into, the asterisk is best used for consistency - from every perspective. An x is only used in gradeschool math, and cross-products. – Izkata Mar 3 '12 at 20:11

Compare:

x x y = c - Bad for obvious reasons

x × y = c - Also bad, but less so. It looks like (x^x)*y (x raised to the x, times y)

x * y = c - I would consider this the obvious choice, especially since using dot for multiplication is standard for Pre-Algebra and beyond. (Roughly age 13 or 14 and older in the US)

• x × y = c is not bad, it is very much standard. – Matt Rockwell Nov 16 '11 at 16:58