The Facit Model TK was in production between 1936 and 1954. It replaced the Model T, to which it is very bsimilar; the main difference being the provision of a feature called sliding quotient coupling, which enables the dividend and the divisor to be input without the requirement to pad them out with zeroes.
This machine was only slightly different from its direct successors (Models NTK and C1-13), which except for minor mechanical refinements and styling changes, were essentially the same. Thus it can be said that a design from the 1930s was produced without interruption with only slight modifications until the early 1970s – a remarkably long time.
