Four phone interviews. Quality of the interviewers varied: Two were pretty reasonable. The other two seemed not to care very much, and I got the impression that they weren't paying attention to the interview. (One flat out told me that he was going to keep working on something at his trading desk *during the interview*.) The questions were very similar to the ones posted here. One thing I'd say is that accuracy matters; They seem to really care about the actual arithmetic in addition to the conceptual solution.