Let x be your score out of 100 points.
Compute the number (x - 23)/14. (Where this formula comes from.)
The result is a number that represents the grade in terms of the standard
It is the *numerical* score that is used in course grade calculation.
That is, the difference between 2.4999 and 2.5001 is no greater than the difference between 2.5001 and 2.5003.
Numerical values less than -1 are rounded up to -1 and those above 5 are rounded down to 5.
Here is a picture of the class results. The columns represent the number of students getting a particular score, using the scale on the left.