Thought I'd chime in here. Besides I haven't posted here in a long while
When I look at a page of numbers or equations, my eyes slide off the page; there's no starting point.
I experience exactly the same phenomenon with poetry, and, thanks to the internet, a "wall of text". I have tried very hard over the years, I just can't do math or poetry.
It's like my eyes have their own little panic attack!
I can fully relate to that with history. I could never understand the context of historical events. The worst is when I'm asked to synthesize information. "If this historical figure were in this situation, what would he do?" kind of questions. Like you, I've tried very hard but I have to read so much into things that it's exhausting, and I still don't retain it for any longer than I need to. Despite my best efforts in college, I could only get, like, 65% in history classes.
But with numbers, I kind of fall in the middle of the number spectrum I guess. I am okay at remembering phone numbers, dates etc. so long as my brain can find a good reason for remembering them. For instance, my own phone number, and the phone numbers of my family and closest friends, I remember well, though sometimes I remember their old phone numbers better than their current ones. Even though I have a smartphone, I'm so used to dialing phone numbers. If a number changes, I can often put it to memory if I make a conscious effort to do it, and by that point I'm too lazy to update/add them to my phone haha. But birthdays were never a huge deal, I mean we celebrate them but we don't do anything extravagant. So I sometimes forget them.
When I was a kid I loved simple mental math. In fact I was so perplexed by the vertical method of adding/subtracting numbers right to left that I mentally taught myself how to do it from left to right by imagining a number line grid and counting on that instead. I got a lot of stuff wrong at first and was often asked if I actually understood what I was doing, but by the time we were moving on to more advanced stuff, I was good enough at my mental way that I could get better grades than my class, and my brain didn't feel like jello when I was done. Multiplication/division was harder, but if I remember right I also tried to come up with mental tricks for those. They weren't as effective though.
The hard part of algebra for me was figuring out which steps to perform when. The abstractness of it got to me. Once I figured out what to do though, my mental math would take over and I'd actually at least somewhat enjoy solving the problem. This was such an obvious thing that even my math teachers noticed it, but it didn't save me all the time. One time I got a C on a test, and when going over it with me, the teacher told me that she didn't think a C was a reflection of my abilities. She knew I was really good with mental math and she could guess why I made the mistakes I made, but because I didn't show my work, she couldn't be sure and thus couldn't give me partial credit, which would've brought my grade up significantly.
Even now I use simple math a lot as my special interests lie in music technology, which can often have strong mathematical ties. I'm not deep into it though, I'm not working with logs and exponents often. To be honest I'm finding myself using a calculator more and more, especially when I have easy access to one, because the novelty of doing things in my head is wearing off.
Sometimes when working through an interesting task, I get to the point where I know that what I'm doing is working, but I lose perspective and context i.e. I know each step is required and I know it gives me something I need, but I forget what that is and why it works. This is beyond frustrating when trying to explain how I do things to people who don't know much about it, or when trying to learn a new formula which is too heavy on abstract concepts. It's one of those classic aspie dilemmas I suppose.
