The two things are not related. iWork '13 changes the asterisk to a little "x" character that stands for the multiply operator, not the same code as for a lower case X, but it looks a lot like one. Also, a slash character that we normally associate with division is changed into the divide symbol, ÷. (A dash with dots above and below.)
This was all just a waste of time on the part of the programmers, in my opinion, and a source of confusion for us.
That business has nothing to do with why you are having trouble multplying the contents of D8 by 20%. What is the content of D8? What exactly is your result?