Kunikida was currently scolding the class about you guys somehow not understanding 'simple math', because you guys aren't grade schoolers, so he expects you to understand immediately how to do Rational and irrational numbers. But currently, someone somehow didn't understand what 6 x 7 was.

"WHAT IS 6 X 7!?"

He yells at the kid. Because he should already know it because of the grade y'all are in currently.