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
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.