I have what's a major case of "Dyscalculai" (number dyslexia) and for years struggled to do the simplest, basic maths and even still I can't add up in my head and have to count out loose change like a small child.
Affects everything from struggling to follow instructions or recipes because the measurements and units just blend into one and throw me all over.
One of my oldest friends is a psychologist and saw me working out how much two cans of coke for 75p each would be and was so amazed I actually needed to work that out she had me complete a few tests. Official diagnosis - PROPER SHIT BITCH.
I cannot work with numbers, follow graphs and charts and have to ask someone to double check certain equipment and things like hoists and slings.
When I'm working with numbers I use my working hand and use to punch in digits and don't swap from letters to keys if poss. Don't use the numbers along the top of a keyboard though use the number pad only.
I'm a touch typist and smash out words and don't even think or look at my hands but if I have to add numbers it means stopping, taking my working hand (left) and going to the number pad.
It would have helped if I knew it was even a thing back when I was a kid because I struggled but knowing it is actually a thing and not just me being a dumb-ass means I can at least go "I'm not thick - it's a thing"