My boys simply do online math drills. For an auditory learner, I’d have him say the problem and the answer out loud.
A lady from the WTM boards long ago posted about a memorization technique she used. It focuses on using the child’s dominant ear, which is usually the same side as the hand the child writes with. You record the memory work, and have the child listen to it with headphones, but only in the dominant ear.
She used to have a website where she explained more about why this was helpful, but I can’t seem to find it.
I often feel like I’m in the minority with this opinion, but I’ve never cared for learning math facts with songs. It just seems to add too much additional information that the child has to sort through to find the answer to a problem.