Does he really need to memorize his multiplication facts yet? Some kids just really aren't ready developmentally for quick math facts until they are a little older - some as old as 5th/6th grade. My 2e ds who has dysgraphia was really challenged with memorizing math facts, but he had a huge leap where he suddenly got much quicker at it that I think was associated with maturing executive function as he neared puberty (that's all just a guess on my part, but I think no amount of making him try to memorize them so that he would have quicker recall would have worked until he was at the stage where his brain was ready for it.
My dd8 has a weakness with associative memory, and she's actually not that bad with math facts (compared to my ds at 8).... but fwiw it's been recommended that she be given a multiplication chart at her desk at school and allowed to use it for math work during class until she has the facts committed to memory. Our ds is older but has an accommodation to be able to use his calculator for math facts etc.
I don't think it's unreasonable at 8, if you have a child with a disability such as ADHD, to pull back a little bit on the math facts and give them an accommodation, then try to focus on quick recall of the facts 1-2 years from now. But that's just me
Best wishes,
polarbear
