1+2+3+4+5+6+7+8+9=10 is not good mathmatics for Kishimoto. And Rowling... her books fail a lot at timeline and simple maths. There are a lot of "Flints" aka errors in the timeline or adding up of years. They are called Flint after a prime example. The Slytherin Keeper Flint was suppose to have graduated earlier than what he did. She misremember what grade he was in, so he's still around a year or too after he should be gone.


So... when I say they both went to the same math classes...I'm kinda saying they both are not showing great math skills all the time.