> how many times do you calculate "X per year" in your head? i do it multiple times per day, and not just at work. Seldom enough that I 'calculate it in my hea

> how many times do you calculate "X per year" in your head? i do it multiple times per day, and not just at work. Seldom enough that I 'calculate it in my head' (as your comment suggests you do too) rather than memorise the 12x table. But then again I grew up in metric country that only bothered with drilling kids up to the 10x table at school. Never had to worry about feet to inches conversions very often either.