I think it's common for bright math students to love the deep understanding type tasks (for example, dive into the concept of multiplication and figuring out the answers) and get bored with memorization. Still, they need to know math facts to do more complex math without getting tripped up.
Does he need to know right away?
I have a DS7 that also tested gifted in math areas but has average WMI and low processing speed. He's great at math, but not fast. So, he really needs to know math facts and I also really tried to help him, but I've stopped doing that for now.
When he was 5 I told him he had to memorize addition/subtraction before I would teach him to multiply. He sat on the bench at K recess and taught himself his full multiplication tables by himself. :P So, he knew multiplication better than addition for a while. Ugh!
What finally worked was to just have him do a lot of addition and subtraction. Time and time again. Eventually he (mostly) knew it. Dreambox, IXL, there were a few competitive addition practice games on the ipad where he'd race against us to do addition and subtraction. Sheer practice and he had it. He would not sit down and memorize it though and we had to stop asking after it started to make him dread math.
Maybe you can come at it from several angles and just see what clicks? Good luck!
I also think the Beast Academy suggestion may click with him... the tricks for memorizing some of the multiplication tables are neat.
