The inch in the Imperial system is based on 10 so the 12 in the foot is based on inches which are based on the number 10.
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Not sure what you are trying to say there. A little reading on Wiki finds the following about an inch.
An Anglo-Saxon unit of length was the barleycorn. After 1066, 1 inch was equal to 3 barleycorns, which continued to be its legal definition for several centuries, with the barleycorn being the base unit.[14] One of the earliest such definitions is that of 1324, where the legal definition of the inch was set out in a statute of Edward II of England, defining it as "three grains of barley, dry and round, placed end to end, lengthwise".
and
In 1930, the British Standards Institution adopted an inch of exactly 25.4 mm. The American Standards Association followed suit in 1933. By 1935, industry in 16 countries had adopted the "industrial inch" as it came to be known.
As to CNC's: an inch based system typically has a resolution of .0001" as you mentioned. A metric system is typically .001mm. So which one is higher resolution?
Jerry
