I'm not sure why you consider the twelve times table to be a waste of time in a decimal age Mamie. Surely we multiply and divide all sorts of things – not just those that work in tens. In fact, when I was at primary school we learned our tables up to the sixteen times table. You never know when these things will be useful. For example, tablespoons measure 15 ml so I find the fifteen times table useful; illustrated books are printed in 16-page signatures, so I find the sixteen times table useful; American cooks still use pounds and ounces, so the sixteen times table is again useful and ditto for American pints (which contain 16 fl oz). No doubt there are people in other fields who do similar sums al the time.