I had that problem pretty much entirely throughout my education. In my first year chemistry class in college I was often essentially teaching the (perfectly competent) tutor things she knew less well than I; nonetheless I was unable to pass the class because of exactly that problem. (If the tests had been untimed I could have gone through and checked my work several times until I caught all the transposed and otherwise misplaced numbers. I did fine in the untimed class assignments; they just took me a while longer than some people.)

I have wondered for close to thirty years if I have undiagnosed disgraphia.