Memorizing the tables past 12 is something stressed in older education, but isn't necessary. It really comes down to knowing strategies to simplify the calculat

Memorizing the tables past 12 is something stressed in older education, but isn't necessary. It really comes down to knowing strategies to simplify the calculation. If you can round the operands to a more easily used number, say 23 becomes 22 or 20, it's much simpler to do the mental math.