To wish I didn't have to explain that I can count?

[Sugarditch04]

I've worked at the same place for five years.
I'm looking for work but it is a high unemployment rural area so to find something is rare enough but due to childcare I need certain days on and off so I can both look after my dd and earn enough money for us to live.

When I got this job I had to obviously let them know my experience and qualifications. I had experience but I have no qualifications
I won't let it hold me back, I perform well and do the job without a hitch. I am often the most senior person in the workplace unless my manager is in.
My manager is a dick. Every week there's a nasty comment. Last week it was

"We need to do a stock count, co worker name can you start counting up x and y there should be about 80 I don't want my name to do it as she can't count beyond 10"

Always something like that and always in front of other people. To the point where my co workers are often surprised that yes I can count and do everything else when manager fucks off on holiday for 3 weeks at 2 days notice
I can count fine, as well as read, understand and make graphs and charts, do basic algebra, add, subtract and divide.
Im also trusted to count cash and do a weekly bank run, but I'm not trusted to count to approximately 80?

I'm by no means an expert and if I sat a maths GCSE today I'd probably fail but it's perfectly sufficient for my job!
Aibu to wish people wouldn't take the piss?

Doing an organised GCSE Maths course is obviously not on the cards.

However, you sound numerate and organised, and you might be able to teach yourself with a good textbook, and then just sit the exam next June as an external candidate.

Here are some sites to look into:
www.learndirect.com/help/about-learndirect/our-products-and-services/qualifications/

www.learndirect.com/maths-english-it/maths/free-maths-qualification

I recommend Khan Academy for teaching yourself maths. It is totally free, and it is a fantastic resource, whatever your level of numeracy. www.khanacademy.org/

BBC bitesize is also very helpful. www.bbc.co.uk/education/subjects/z6pfb9q

Why are all these people making recommendations? If her boss' bullying comprised of calling her fat, would the same posters suggest weight loss programmes and techniques?

Nope, but it will help her get a different job which is what the OP wants. There's no HR, boss won't listen so she's stuck. Unless she want to level a bullying complaint and potentially go to and ET it's her best option.

Is this a thing with bullying bosses? I have a degree and many years in the field but my boss (just the once) made a nasty, belittling remark about me not being able to count past ten.

Way to motivate people,
Bosses! Way to promote company loyalty. He's a dick, it's not you, it's 100% him. I know this, as I can do a bit of math.

Can you join a union and then seek advice from the union rep? Maybe a letter from their legal dept outlining what consitutes appropriate workplace behaviour and possible implications of bring sued for constructive dismissal might bring an end to this behaviour.
Failing that, maybe talk to citizens advice.

Have tried citizens advice - the options they gave weren't very useful.
I don't think GCSEs would actually help my employability for reasons stated upthread and in addition to that it's not viable for me to sit them. Thanks for all of the advice however unwelcome some of it was

"...she can't count beyond 10"
"We can always count on you to come up with the same old joke though!"