I've been using Moodle 1.9.10 and I've worked a lot with calculated quiz questions. The edit Datasets page has been a difficult one, but I know appreciate those two lines of information Murad mentioned.
As I understand it, the first line shows the range of values (max and min)Moodle will accept as correct, based on the tolerance value set on the first page of the question.
The second line shows the effect of the significant figure (SF)/decimal places (DP) setting (1st editing page). E.g. 550 = 600 if rounded to 1 SF. I usually set this to 2 DP or 3 SF.
This is why the 2nd example has given back an error - the rounded figure is now outside the limits of the maximum and minimum.
Hope you find this helpful.