[II2II]

> Whenever we had to learn the times tables or the squares at school, I would just work them out in my head instead of memorizing them.

I took a slightly different approach: memorize what is important.

For some reason, they wanted us to memorize the times table up to 12 when I was a kid. I quickly recognized that it was only important to memorize it up to 9, and even then there were patterns. Why is 9 more important than 12? Because it is incredibly inefficient to figure out a product each time you need it, but the rules for multi-digit multiplication were generals whereas the rules for single-digit multiplication only worked for single digit (and were necessary for multi-digit multiplication anyway). The trick is to figure out when the efficiency outweighs inefficiency.