My mother is somewhat technophobic and incredibly bad at math. She always has been. She took biology, but didn't do chemistry because she was advised that she wouldn't be able to manage the math in it, and knowing her abilities I completely agree. She uses very basic math regularly, because she makes quilts by sewing small squares together (after sewing a bunch of small stuffed squares). So, she figures out how many squares she wants by working out how many on each side and then multiplying. She can do this, because she has very basic math skills. She does this using pen and paper. What I find sad is that while she can do this, she has never learned how to use a calculator. So if the math problem is too complex, she just asks someone else to do it (for quilting it never is, but life sometimes has more complex things).

I can do reasonable levels of math (I had problems learning calculus but did quite well before then) using pen and paper, but my working memory is so tiny that I have difficulty doing math in my head (or remembering phone numbers or small lists, etc.) My problem is that while I'm solving the problem, some part of the info has fallen out of my working memory. But I can do reasonable approximations for most real world problems. When I was shopping with my mother as a child, I would be the one to figure out that if the item was X% off then the cost would be about $Y.

Sometimes I think my mother would have been better off with even less ability to do math on pen and paper, but feeling comfortable with a calculator. They didn't have them when she was growing up, so it wasn't an option. But these days you can get a cheap little credit card sized calculator that will easily do any basic math you've got as long as you know what numbers and what operations to feed it.