Nigel: Not to mention 20 shillings in a pound! Or hundredweight in a ton.

Interestingly, in the late 70s my mum was a bit curious about the "funny lookin' number stuff" I was messing about with. So I thought I'd have a go at explaining Octal and Hexadecimal to her, expecting it would be tough for her to grasp.

She immediately said "oh, the's nowt to it. It's nobbut stoans te' 'undredweight an' ahnces te' pahnds, i'n't it?"

When you think about imperial measurements, anyone who can work with the full range should have no problems at all with changing bases...there are 5 (arguably 6, even more if you include obsolete units like Cloves, Tods and Sacks) "normal" shifts in base just going through the imperial weight system.