How old is he?
That makes a big difference.
I was beat with a belt every night during homework to try and "make" me learn multiplication. I stopped learning it at 6X8=48.
I failed college algebra in beginning algebra 2 times at 2 different colleges. I got in with an educational psychologist and she figured out how to get past my mental block. It was by color coding everything.
Positive numbers were green, negative numbers were red, and other stuff was other colors.
So, for a simple subtraction problem it went like this.
10 (10 green) -7 ( -7 red) = (= black) 3 (3 blue)
I stopped seeing a math problem that I couldn't understand and saw it differently. She wrote a paper about this in a professional journal, well, she asked my permission formally.
My point is each person learns differently. Go have kiddo do the quizzes on learning styles and find out his 2 most prominent learning styles. Then work on multiplication using them.
I truly think most kids learn by seeing and hearing. So having him repeat the whole section out loud is what they usually do.
For instance, when we were in the car I'd have the kids spelling words for that week over the visor.
I would ask "her" to spell....beautiful. She would have to spell it out loud. Then I'd skip down to a word way down the list. Switching it up. She has the highest spelling test scores in her grade but I am a near perfect speller.
I had her do multiplication like this. We did do random math problems too, like the spelling words but not as often.
Say all the 5 multiplication...I can't remember what I said but it was meant to get her to say 1.5=5, 2.5=10, 3.5=15 and so forth. If they have a multiplication problem 5.5=25 in front of them they need to be able to hear themselves saying 5.5=25 so they can pull it from long term memory.
There are many ways to teach math. Tracing the numbers in sand gives them several sensory inputs. The feel of the sand, the shape of the numbers, the feel of their finger making the shape. It enters their brain in the backdoor sort of. You can ask the teacher for more ideas on this.
Having then do woodworking, using the measurements you set out, say.....I need 3 feet of this stick. How many inches are in a foot. 12 is correct. So if I need 3 feet of this stick what's that look like. Then they can write the math down or trace it in sawdust.
Cooking is another way. A quarter cup of butter is how many tablespoons. It's on the butter wrapper but if they're working on math they get to say it out loud, how they figure it up. How many cups in 32 ounces. You can do it from the other end to get multiplication. Or make 2 boxes of something so they can multiply by 2.
Find innovative ways to get it in there. Saying it by rote is boring but necessary, that's how it gets there. By doing the same thing over and over and over again it becomes ingrained in our brains. By doing it where it's a blast is so much more fun.
Both ways are needed so they make wiring connecting it all up. If they miss that part they have the knowledge but can't access it.