Not everyone knows their 1x tables

I have been told that I can be too harsh on people and their (in)ability to complete simple arithmetic without assistance. Last year, I shared the following exchange with friends:

Stranger at supermarket: Oh, your daughter is soooooooooooo cute, how old is she?
Me: Four months.
Stranger at supermarket: Oh my god, another couple were just here with a four-month baby, that’s like so funny.
Me: I guess there were a lot of people getting busy thirteen months ago.
Stranger at supermarket: (gaping) Wow, did you just do that in your head? You are like so good at maths.

Most agreed that this was a ridiculous reaction to my ability to quickly add nine and four. But some said I was being too harsh on Stranger at supermarket. So, Stranger at supermarket, I apologise.

But, surely, you must agree that we should all know our 1x tables. Yes, our 1x tables.

Me at pharmacy: I’d just like to return these crutches.
Pharmacy checkout person: Okay, when did you hire them?
Me: Twelve days ago. I originally hired them for a week, so I’ve had them for five extra days.
Pharmacy checkout person: Not a worry. Now, our weekly hire charge is seven dollars, so (pulls out calculator) the charge for the extra five days is… (tap, tap, tap) um… (tap, tap, tap) five dollars.
Me: (dumbfounded silence)
Pharmacy checkout person: (mistaking my silence for concern about the money) But don’t worry, you paid a deposit of 25 dollars, so we’ll just take it out of that. So… (tap, tap, tap) we’ll be giving you… (tap, tap, tap) 20 dollars back.
Me: Um… yes, great. (Transaction continues)

Ridiculous, right? Perhaps people should switch off their iPhones, throw out the computers and calculators, and just think about things every once in a while. Or perhaps I should be grateful that a diligent employee wanted to ensure I was paying the right amount, and extend my Stranger at supermarket apology to include Pharmacy checkout person.