I can't remember exactly how many, there was quite a few, but when compared to the almost infinite complexity of a personality it is just a handful of questions.
Also if you visit
The Myers & Briggs Foundation - MBTI® Basics and read about the different personality types, I find I can mostly relate to various introverted types and this is probably the case with many people, I say mostly as none 100% describe me accurately and I don't even agree with everything on ISTJ that is supposed to be my personality, for instance I'm most definitely not "organized". None of the personalities will totally describe a lot of people because it is impossible to put people's almost infinitely complex personalities into just 16 categories and even if one category does appear to correctly describe a person, there will usually be other personality traits that aren't listed that also apply and some of these may even be listed on another personality type. Even when you consider the split of introverted and extroverted personalities, well there is no definite split of one or the other, for instance some people maybe be right down the middle, yes autistic people are more likely to be introverted, but even then some are more introverted than others. You could however say this about all the personality traits, for instance "factual", again there is no definite split of people who are factual or non factual as people are at varying points.