@falcennial @infobeautiful In one of them, the child "counts in eights", 12 times, and in the other it "counts in twelves", 8 times, and it finds one easier than the other. Of course, multiplication is commutative so the child could swap one against the other, but based on practicing with my children, that is something that does not come naturally at all and the child will prefer sticking to the same order (say, counting in A if the task is A \times B) for all multiplications, even if swapping the order would make the task easier. The mental costs of the swap-or-not decision are too high.