What does the "Number Questions" column mean, under Manage → Users → Individual User? For example, "2/3" appears in the "Number Questions" column for a particular user.
The 2 in the 2/3 indicates how many items the given user is allowed to review. The 3 indicates how many other reviewers have also been given the same assignment.
If there were 20 items in the assignment, the value would read 20/3, or 20 Questions among 3 Reviewers.