This is my second time appearing for GMAT. Last time i got more than 650 on the GMAT prep, but some how got only 500 on the actual GMAT. Yesterday, i took the new GMAT prep test, i got 640. The interesting thing is i got 13 incorrect in math and 17 incorrect in verbal but i still got 45 in math and 34 in verbal. Is the score in GMAT prep always calculated properly or is it possible that the software has a bug. The other day i took some other test, in which i only got 6 incorrect still i only got 43 in math. Some one please help- is 640 a real indicator for my score.. ?
I'd consider GMAT prep tests as most reliable tests and a good indicator of real GMAT. There's no bug in the software. don't worry.
But there are some reasons why one could get marginally less or more marks in actual GMAT than GMAT Prep s/w...

















