Re: We use base 10 for a reason
>I did O-levels (pre GCSE!) in the good old pounds, shillings and pence days. I had to learn how to add, subtract, multiply and divide sums in pounds, shillings and pence
I was a kid in the 1970s and just started school the year before decimalisation. I remember our 'times tables' books went up to 12, but we only ever were taught multiplication up to 10 times.
I guess learning to multiply by twelve was, all of a sudden, no longer a required skill, bit they hadn't updated the text books yet.
BTW: being a child of the decimal era, I always just thought that pre-decimal coinage was just another example of the previous generation making things unnecessarily complicated. It wasn't til much later in adult life that it suddenly occurred to me one day that 12 is divisible by 2,3,4 and 6, whilst 10 is only divisible by 2 and 5 —and I realised there was a method to the old folks' madness, after all.