I do have some of this kind of little maths memorized, but only enough that there's usually one near by - e.g. 7*5 = 35, so if I need 7*6 all I have to do is add another 7 to that one 😁
Obviously factor 10 is also readily avaliable, so I might get to 7*8 by going "So that's 70-2*7, so 14, that puts me at 60-4, that's 56"