Well, I'm an INTJ but my N and S are relatively close (I test ast ISTJ about 15% of time) and math did come to me quite naturally. I think it came to me naturally because as a child and later as an adult because I always wanted to put things into order and math can help to accomplish that (like building something).

My ISTJ friends were always very good at math and tend to be quite talented when it comes to working through the details of a problem/project. However, they seem to have a terrible time applying those concepts beyond math problems. They can understand what's going on, but putting that understanding into 3 dimensions can be a challenge for them.

Bottom line is that I think there is something to be said for the suggestion that an N/S balance helps with math. The S will help you to understand the details, but the N will help to apply those concepts in unique ways.