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.