One day at school

I looked at the first row. Most of the numbers were zeros. I glanced below. The numbers there were all above five. The idea was to subtract the lower row from the one on top. At this point, let me clarify that this was not my idea of how to spend time on a bright sunny morning. I am a simple, fun-loving person. This convoluted mode of brain torture was my teacher’s idea of fun. I could see him dozing off in his chair while we clueless students struggled to find answers to his problems.
Zero minus six, or was it six minus zero? How do I remove something from nothing? I was sure that whosoever invented mathematics was born old and boring. My thoughts wandered back to the problem at hand.
‘Could the answer here be 4 ?’ I thought.
‘Maybe 5,’ my equally confused consciousness replied.
I wrote six there because I trusted no one. I moved on to the next column.