This is unusual scale that only the exam makers truly understand. There is no way of guessing how many questions out of the number you're tested on to know how many will give you a passing score. The goal is to insure that you're not just studying for 3 out of 5 domains thinking that it's enough. Because they also add in beta questions that may not even count towards the score. You'll never know if you're being graded on 50 out of 100 they ask or 36 of 51. They work off the assumption that you should know 100% of all objectives being asked. The key is never leave a question blank. Because it does not count against you if you do...but it does reduce the over number of possible right answers you might have answered. Which means that each question will be worth more; and that means that you can miss less.
The range of scores is between 100 - 900. I believe the 100 represents the low range of scores and that the scores do not begin with ZERO.