Times tables/multiplication tables. I learnt them when I was really young - I had pneumonia as a child and I would have my back massaged for a short while…during this, I would read thetimes tables… being able to do any multiplication like speech has been invaluable. Raising my own kids and working with them to learn them… with one knowing them well and two not so well and unwilling to learn them have now come into high school and working with fractions etc it is having a toll… times tables