Create a binary file with roll number, name and marks. Input a roll number and update the marks

import os

def update_marks(roll_number, marks):
  f = open("students_marks.dat", "rb+")
  f.seek(roll_number * 24)
  # get rid of the trailing \n
  name = f.read(20).strip()
  f.seek(roll_number * 24)
  f.write(name + str(marks))
  f.close()