A broken tooth on gear B creates one disturbance every full rotation of gear B.
Gear B has 20 teeth, so 1 broken tooth produces 1 fault per rotation.
The take-up roller pulls fabric according to its circumference.
Given roller circumference = 40 cm.
Thus, one rotation of gear B corresponds to 40 cm of fabric being wound.
Therefore, the wavelength of the repeating fault is equal to the roller circumference.
\[
\text{Wavelength} = 40 \, \text{cm}
\]
Hence, the wavelength in integer form is 40.
Final Answer: 40