GPA Calculation

<p>My son's high school doesn't rank and counts a "B+" as a 3; "A" as 3.5 and "A+" as 4.0. This seems kind of off from what I remember in college and grad school where B+ was a 3.5. Do many high schools use this system?</p>

<p>If not, are colleges aware of an individual school's grading system and do they recompute the average?</p>