A. W. Faber Model 366
The A. W. Faber Model 366 was an unusual model of slide rule, manufactured in Germany by the A. W. Faber Company around 1909, with scales that followed a system invented by Johannes Schumacher (1858–1930) that used discrete logarithms to calculate products of integers without approximation. The Model 366 is notable for its table of numbers, mapping the numbers 1 to 100 to a permutation of the numbers 0 to 99 in a pattern based on discrete logarithms.