This Human Calculator Dude Just Ruined My Day

I hate people like this who show me just how stupid I really am. I need to whip my phone out just to figure out the tip on my bar tab. If I could do math like this I'd be just like this guy, struttin' in front of students and teachers and math professors who think they're king shit and just shovin' it in their face. "Hey kids, you think your teacher's smart? Uh-uh. Check out the big brain on the Bahtendah!" Never gonna happen though. The closest I'll get is to bring some dude like this into the pub with me and announce to everyone "Hey look at the big brain I found!" Maybe use him to win a few rounds on math bets. Thing is, he'll need to stick around to figure out the tip.