My job ATM requires a decent amount of number crunching and it's satisfying to be able to do stuff faster in my head than using a calculator. Tbh my mental maths is definitely in the 'good' category, but 12 times table? What's the point? If you know your 10 and 2 times tables and you know how to add two things together why would you ever need 12? If somebody says 7*12 to me, I'm not ashamed to admit my brain just goes '70+14'. And tbh the only reason I know my 9x table is because of playing Snake on my old Nokia at level 9 difficulty and not being particularly good at it...