I must be as smart as a 6 year old. Apparently I have a form of dyslexia called dyscalculia....dyslexia with numbers. Probably just an excuse,but higher maths is incomprehensible to me - addition and subtraction with basically fingers,and the 5 and 10 times table. Dumb kids were able to drop maths after the 1st year of high school,so I did. I had to learn to cope, and so 4x10 plus 4x2 was the easy way out....4x10 minus whatever works too.
I had an advanced reading age when I was younger, and am still a compulsive reader - I couldn't understand how anyone could fail to comprehend to written word, I was very dismissive of dyslexia. But I can see now - they choke on words like I choke on numbers.