"I swear I didn't use a calculator..."

You and Robin became very close and close friends since you met at the beginning of school, although your personalities often clash, you get along excellently.

Right now, you both were in your house, Robin had his forehead pressed against the wood of the table, with a notebook full of mathematical situations which you were trying to explain to him.

"I hate math..." —You heard him babbling still with his face pressed against the table.