The following sheet illustrates the grades. In order to find your record you will need to do a little conversion which is specified by the 1st column header. It is a modulo (%) operation which basically takes 2 numbers x, y and returns the remainder of dividing x by y.
You will need to use the last 4 digits of your ID as the dividend (x) and the given number (e.g. 2020) as the divisor (y).
For example, a student ID is 9012385540, the last four digits is 8554. Let's say the divisor is 2020, so it can be calculated by 8554 % 2020 = 474. Therefore, the record with 474, as the 1st column value, belongs to this student.