Fantastic score! Congratulations! That's 99th percentile.
The official GMAC response is that each question you leave unanswered penalizes you 3 percentile points for that section. E.g. you got Q49, that's 86th percentile these days
, and Q50 is 93rd. Depending on your position, you may have not lost any points but most likely you would had Q50. (Similar to MGMAT, when you get up that high, the penalty can be much higher).
Assuming you would have gotten Q50 and V44, that's in between 760 and 770, you could still have scored a 760 if you had a "soft" 50 or "soft" 44.
Unfortunately one more tip - it is wise to mark any answer on the last few questions before you start solving. Even if you marked an answer but did NOT confirm, it will still count at the end, similar to the AWA essays that will count when the time runs out, even if you do not click the Submit button.
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