One evening, Sam and Amber go into an underground passage to help Uncle Zak fix a power failure. Fortunately, there are metre markings on the wall and Sam and Amber estimate about 300m of power cable has been eaten away by Weebs. Uncle Zak needs to know exactly how much cable has been damaged, so the children call Numberella, who shows them how to work out the difference between two numbers. Power is restored, but mysteriously fails again later in the evening.