I recall obtaining 98% / 100% in my O Level exam in Motor engineering, yes i was if not the first certainly one of them in the UK that took the exam as it was introduced into Secondary Modern, when my father viewed the results he went balistic because i had not achieved 100% in this field, after all i had worked and played in our family garage since i was 9 years of age.
My father contacted the school to investigate why i had only resulted a 98%, the Teacher informed him i could not explain why we required Tappet clearance, sure i new we had to have tappet clearance because i had reset so many, but WHY the clearance had to be there (for heat expansion) was beyond me, rather than be happy with 98, he was unhappy about the lost 2%......thats Fathers for you