The top knob sets the master clock, ranging from 40 to 200 BPM. The top jack outputs the master clock as 16th notes.
The middle and bottom knobs either multiply or divide the master clock, depending on whether the knob is turned clockwise (multiplication) or anti-clockwise (division) from the centre position. At 12 o'clock they output the same clock as the master, that is to say they multiply/divide by 1.
The middle knob values are 1 in the centre, then 2, 3, 4, 6, or 8 times as you move away from 12 o'clock.
The bottom knob outputs 1, 2, 4, 8, 12 or 24 times multiplication or division.
The name (Stoicheia, or Elements) comes from the title of Euclid's book Elements in which the algorithm was first described.