I got used to them so quickly I was amazed, I could see things close up and far away easily. I had been taking my glasses off for anything close up (I'm very nearsighted) and now I didn't have to. I'd been fighting going into bifocals for years and finally had to admit I had to do something. The only real adjustment I had was getting used to keeping my glasses on. I still read without my glasses a lot and sometimes knit without them on just because I prefer it. I do find myself tilting my head or the computer screen sometimes to get the best focus. Overall I love them.
I should never overestimate my basic arithmetic skills.