Getting a hex representation for a Numeric

Hello,

I was disappointed to find that there is not an instance method for
Numeric that lets you convert the value to a hexadecimal string.
Luckily, sprintf comes to the rescue to do this!  Can I propose to add
something like this to the standard library?

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class Numeric

   def hex
     sprintf("%X",self)
   end

end
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Or is there already a method that I missed?

Thanks,
Zev