I'd object to the idea that memorizing times tabes is relatively trivial as I've always had trouble memorizing anything. But I too realized a lot of the times t

I'd object to the idea that memorizing times tabes is relatively trivial as I've always had trouble memorizing anything. But I too realized a lot of the times tables are basically "free": the only ones I felt I really had to memorize were 2, 3, 5 and 7 (incidentally, the primes). In fact, I still struggle with the 7 sequence because we learned the times tables in two batches (1-5 and 6-10) and 7 was the only one in the second batch that required actual effort and at the age I mistook the other ones being trivial to deduct with me having become better at memorizing times tables. In retrospect, batching it as learning the primes first (including 1 to ease you into it) and then the rest of the numbers second would have probably helped me a lot by avoiding the feeling of "what the heck, why do I suddenly suck at this again when I just thought I had gotten good at it". But of course the concept of primes is off-limits when teaching basic arithmetic so even hinting there's something special about those numbers was apparently taboo. EDIT: Additionally I'd argue out of the primes, 5 is almost free because of how numbers are represented in decimal (i.e. it just alternates between 0 and 5 and the digits in front of that go up every other time) and doubling is fairly intuitive to reason about (take what you have and add the same amount again) so it's just 3 and 7 that are weird.