Not sure where to post this question, if it's even a question? But it does have to do with attention issues, possibly more, so this might be the right place.

DS5.8 has been homeschooled since Thanksgiving (Kindergarten). He has always been a mathy kid, figured out addition and subtraction early on (by the time he was 4) but has stalled once he started public K and even regressed. It took about a month after pulling him out of school to homeschool to get him back where he was and then he just slowly started going forward again. He clearly has issues with attention that we've been seeing over the years (I don't want to say full blown ADD but it's very possible). He has days when he can tell me what 9 + 9 is right off the bat, he will look at the clock and see it's 3:09 and tell me we have to leave in 21 minutes if we need to go somewhere at 3:30, but most days he has trouble telling me what 5 + 6 is. He's been doing Dreambox learning quite seriously the last couple of months and while he didn't like the Kidnergarten section of it and early 1st grade, now that he's hit 2nd grade concepts, he loves it and wants to use it every day. He understands how hundreds work, he's starting to play around with multiplication, he's been able to understand a lot about fractions for a long time now but the basic facts are always an issue. It's like he enters this fog and can't think. So when I saw how frustrated he was with this, I told him USE YOUR FINGERS ... we're homeschooling so I don't care how he gets to the number, practice makes perfect, right? Well, his 10 and my 10 fingers can only get him to a certain point, so I was at Ikea last week and got an Abacus there, gave it to him and he was so excited! He uses it to help him with the 2nd grade math every day. And now I'm getting to my questions ...
Let's say he'll have a problem 157 + 9 = ? ... and I just ONCE showed him how he can add 7 + 9 and go from there to figure out the answer. And he loves to use the abacus to figure out the 7 + 9 when it's his off day and his basic math fact calculator in that brain of his isn't working and he'll give me the answer to the whole problem. Or yesterday, he was comparing which one of the two is bigger ... e.g. N+35+10 and N+45-5 and all he asked me was "Why is there an N?" So I explained it's just like if he had the same number (any number) on both sides and he instantly understood the concept and went with it. Most days I don't even explain anything to him and let him work his way through everything. So, the question is, is it OK to let him use the abacus (or other ways of getting to the basic answers so he can work on the more challenging problems) or do I need to stop what we've been doing and just concentrate on drilling the basics? And is it possible there is some sort of an issue that's causing him to not be able to recall the easy answers but he can still easily apply harder concepts? In a way, we're having similar issue with reading. He can figure out phonetically how to read many words but sight words are a big deal. He just can't seem to recall them at all, with few exceptions. Sometimes I see him looking at easy math and he has that same blank look on his face like he can't see it and it's RIGHT THERE.

I remember when I was little, well, not just little, even now that I'm an adult, I had issues with the basic facts. I was still doing math on my fingers when I was in Math and Science middle school and it never stopped me from being one of the best students. I guess I just learned to compensate. I couldn't remember multiplication tables but was enjoying working with binary numbers as a 7 year old ... and that sort of thing.

Is this going to become an issue? Should I do anything about it or just let it go, knowing he's just a 5 year old kid?