Right. Kids who answer the “wrong way“ from top to bottom got answers 1 and 100 incorrect, but correctly answered questions 2 through 99 and score 98/100.
Kids who read the last question and leave the rest blank get two questions correct for a score of 2/100.
On a typical test the blast radius for a question is limited. There is no convention that getting a question wrong alters the outcome for other questions, too.