My kid just learned by memorizing the results in order. Like: 8, 16, 24, 32, etc. If the problem is 5x8 then she knows its the fifth number in the sequence. Did not take her a lot of time to then learn the whole formula. Now that I think about it, this is like calculating results in a hash table for easy retrieval later.
We used this video (and channel) and it helped lots:
We used this video (and channel) and it helped lots:
https://youtu.be/IjPjks1R6Ng