Academic grading in the United States commonly takes on the form of five letter grades. Traditionally, the grades are A, B, C, D and F — A being the highest and F, denoting failure, the lowest. Numeric to letter grade conversions generally vary from system to system and between academic disciplines. Grade point average ranges standardized test scores and other native systems of measuring academic excellence can be used. "A" corresponds to "mastery" or "excellence", "B" to "good", a "C" is "acceptable" or "average", a "D" is "poor", and an F is "unacceptable" or "failing".