For the Series 65 exam, a score of 72% or greater (94 of 130 questions correct) is required to pass. For the Series 66 exam, a score of 75% or greater (75 of 100 questions correct) is required to pass.
However, some states do require certain scores of up to 85% to be eligible for registration as an IAR. Note that the Series 65 exam and the Series 66 exam have 140 and 110 questions, respectively, but 10 of the questions do not count towards your scoring.