Number is related to System. System is related to Trade. Custom is a type of Trade. Costume is etymologically related to Custom. 
Tv is related to Speaker. Speaker is related to Noise. Noise is related to Wave. 
Number <--RelatedTo--> System <--RelatedTo--> Trade <--IsA-- Custom <--EtymologicallyRelatedTo-- Costume 
Tv <--RelatedTo--> Speaker <--RelatedTo--> Noise <--RelatedTo--> Wave 