I participated in a math competition back in elementary school

1 boy
1 girl
After class, we were solving problems from 5 PM to 6 PM.
After we finished, the teacher in charge was grading them.
The girl got hers right,
but I got mine wrong.
The teacher told me to go back and solve it again.
I re-solved it and showed him, but it was wrong again.
He told me to solve it yet again,
and when I showed him after re-solving it, it was still wrong.
The teacher was slowly starting to lose his temper.
This happened about 7 times,
but no matter how many times I solved it, I kept getting the same answer.
Eventually, the teacher's volcano erupted,
and I was covered in all sorts of insulting volcanic ash.
The teacher called me over,
and as he was checking them one by one while looking at the answer key,
I caught his eyes trembling.
The answer in the book was an error, and the one I solved was correct.
The teacher asked the girl how she had solved it.
It turned out she didn't want to solve the problem,
so she had just copied the answers from the book.
I never received an apology from the teacher.
However, that girl went on to attend Seoul National University.