We've all been in a situation when we're asked to do math problems in either a timed or highly public situation- whether it be on the blackboard as a 3rd grader or later on in one of those rare times adult life that you actually have to use math.
Not counting my panic attack regarding my one page accounting homework in "business for non-business majors" during grad school, I can count the times on one hand where I've had to do math in a high-pressure situation (and technically a one page homework with a week to complete it and only counting as a minute fraction of my grade isn't really "high pressure" I suppose). Ironically, instead of during any number of my myriad degrees or during my short stint as a trial attorney, my most horrific math experiences came during the time I worked in retail.
I'm going to take a wild shot and say that most people have had either a restaurant or retail job in their lives, and if not, you're likely one of those assholes who treats people in the service industry like shit and therefore have enjoyed many a spit milkshake in your day. I've done both, but the only time I was in direct contact with money was working at the mall.
I actually loved working the cash register. I'm relatively anti-social and don't give two fucks about how a customer is doing, so having a place where I'm required to be that only required interactions with people who had a reason to talk to me (i.e. they wished to purchase things) was perfect. I'd scan the tags, push the total button and the customer would give me money. Then, magically, the register would tell me exactly how much change to give the person requiring no more math than being able to count the number of bills in your hand. Generally this was the sequence of events for person after person.
But at least once a day you'd get the person who THOUGHT they were making your job easier. I'd take their cash, type in the amount and press the button that opened the drawer and told me how much change to make. $8.64, that's easy, I'll just get this 5 over here, and some ones - "Oh, wait, I have *enter unnecessary amount of change here*, HERE!" the customer would say with a smile while handing me a handful of coins.
BUT I'VE ALREADY PUSHED THE TOTAL BUTTON! My eyes get huge as I look at the change in her hand and the bright red $8.64 on the screen. IT'S TOO LATE TO GO BACK. YOU'RE GOING TO HAVE TO FIGURE THIS OUT YOURSELF. My heart races as I look behind the customer and see the line forming. She looks at me like I'm supposed to be thrilled with this development, BUT YOU JUST RUINED EVERYTHING.
Doesn't she know it tells me how much change to give her back? Didn't she see I'd pressed the button already?? I'm working retail for god's sake, there's a reason I'm behind the counter at Juicy Couture instead of at my summer internship with NASA. I can't pull out a pen and paper, which would make this infinitely easier, since there are people waiting. My brain has literally shut down and I am no longer capable of making any kind of decision, whether it be figuring out this lady's change in a timely and unpanicked manner or wiping the look of sheer terror off my face. WHAT IF I GET IT WRONG? EVERYONE WILL HATE ME. I'LL GET FIRED. Then of course everyone will tell me how simple the problem was. THE SHAME.
I feel like screaming "THE LIMIT DOES NOT EXIST" and running out of the room, but somehow I manage to scrape together some form of change after likely an extremely excessive amount of time and hand it to the customer with a questioning look, waiting for her to tell me that I was shorting her $45. When she doesn't resist my chosen amount, I breathe a sigh of relief while at the same time wanting to hit her with a broom for causing all that unnecessary anxiety. Then I look to my left and see the girl who can barely spell her name and has told me she's failing this or that class in community college handle the EXACT SAME SITUATION without a moment's hesitation.
When the next customer hands me her AmEx black card, I want to run around the counter and hug her, patting her hair and just mumbling "Thank you, THANK YOU" for an uncomfortably long period of time.
Some people can't do public speaking, some people can't pee when others are in the bathroom - I can't do math in my head under pressure. Or really ever. Give me a pen and paper and I'm good, but don't expect my brain to be your human calculator.