The Nines System is the informal name for a grading scale often used at educational institutions in English-speaking countries, particularly the United States.
The system owes its name to the fact that each of the top four letter grades in it cover a range of nine points. The minimum passing mark under it is almost always 65%, or five points higher than in the more widely-used Tens System.
The simplest variant of the Nines System is shown below:
92 to 100 = A
83 to 91 = B
74 to 82 = C
65 to 73 = D
Below 65 = F
The option exists to append "+" and "−" signs to each of the letters (but customarily not to the "F"), splitting each of the top four letter grades into three subdivisions, covering a span of three points each as nine is evenly divisible by three.
This yields the following possible grades:
98 to 100 = A+
95 to 97 = A
92 to 94 = A−
89 to 91 = B+
86 to 88 = B
83 to 85 = B−
80 to 82 = C+
77 to 79 = C
74 to 76 = C−
71 to 73 = D+
68 to 70 = D
65 to 67 = D−
Below 65 = F
An "F+" (or "E") grade will sometimes be added, often with a range of 60 to 64, and less commonly an "F−" will exist as well, often for sub-50 grades.
At some institutions the "A+" grade is not recognized, usually due to the fact that the grade point average system is in use; when this scenario arises, the "A+" range shown above may merely be lumped in with the "A," or a more even division of the "A" category may be observed, for example by reckoning 96 to 100 as "A" and 92 to 95 as "A−."