I’d like to create a database for a library but I want to limit how many book a person can check out, any idea how to ?

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What makes myhexadecimalnumber a child of mynumber? which methods does myhexadecimalnumber inherit directly from the mynumber class? what can an instance of the mynumber class do? what can an instance of the myhexadecimalnumber class do? which methods are overridden? why are they overridden? how many examples of overloading are there? why was this done? where is the super keyword used? what is it doing? why isn’t the incoming value set immediately in the second myhexadecimalnumber constructor? how many examples can you find of an inherited method being called?