I must admit that I never had any trouble with imperial measure or pre-decimalisation coinage. There were so many shortcuts available such as a dozen eggs at threepence each are three shillings. I remember feeling relieved when the pound sterling was devalued to $2.40, so 1 penny = 1 US cent. It was only after decimalisation that problems started, and I frequently got the right answer, but with the point in the wrong place, and then I got into IT and had to do everything in octal for quite a few years until we changed to 32-bit and I had to learn hexadecimal!