Academic grading in Nigeria

In Nigeria, the academic grading system scales from A (First class) to F (fail). Below is the grading system of Nigerian schools.
Nigeria offers six years of basic education, three years of junior secondary education, and three years of senior secondary education. If a student chooses to continue higher education this is then four years of tertiary/university education.
Mathematics and English language are compulsory for all students in Nigeria although maths may not be required for some courses in higher institutions - this is dependent on admissions criteria.
Most Common
5-point University (Example - University of Lagos)
Postgraduate
Not all universities use merit score - often pass 40%+ or distinction 70% grade given
Note that NUC (Nigeria University Commission) has expressed strong recommendation to upgrade passing scores in Nigeria universities to 45 which by implication would phase out 40 as pass mark for undergraduate studies. Additionally, to discontinue awarding degrees below 3rd class (if all universities ultimately comply).
Also, at post graduate level, the minimum pass mark for course works is usually 50 (rather than 40).
Whilst some international universities recognise West African Examinations Council (WAEC), many others ask Nigerian students for International Baccalaureate (IB) exams or for students to take five or more Advanced Placement (AP) courses, or possibly the first year of an undergraduate degree at a university known as a foundation (course or diploma) if they gain admission with WAEC.
In Nigeria many students who intend to take international exams do entry exams on top of their WAEC. There are arguments against making Nigerian students who clearly qualify to take an additional admission exam. However many top American and EU universities require choice of IB, SAT or ACT and SAT Math 1 or 2 and a science subject test and letters of recommendation depending on the course the student wishes to take.
The Joint Admissions and Matriculations Board (JAMB) is a Nigerian entrance examination board for tertiary-level institutions . Every year, the Joint Admission and Matriculation Board conducts an examination that determines if a student will be admitted to higher education. All of these candidates must have obtained the West Africa School Certificate, now West African Examinations Council, WAEC, or its equivalent National Examination Council (Nigeria), NECO.
West African School Certificate (WAEC) replaced the West African General Certificate of Education Ordinary and Advanced levels (GCE ‘O’ and ‘A’ levels) in 1989 and is equivalent to high school / upper secondary passout grades in their 6th year of basic education for admission into Colleges. Many students can use this for direct entry into university in Nigeria, Africa and internationally depending on admissions criteria.
General Certificate of Education (GCE)
This is another Nigeria's awarding body school in Nigeria at GCE ‘O’ and ‘A’ levels. The National Common Entrance Examination is administered to pupils in their 6th year of basic education for admission into Colleges. Two examinations are held annually. Students take an exam on Mathematics, General Science and English and various including Social Studies.
Structure of the Examination
The National Common Entrance Examination Questions consist of the following:
PAPER I
Part A – Mathematics and General Science Part B – English and Social Studies
PAPER II Part A – Quantitative and Vocational Aptitude Part B – Verbal Aptitude
Accessibility to Higher Education in Nigeria: The Pains, Problems, and Prospects, January 2020, James Odia, University of Benin