Random Numbers based on the ANU Quantum Random Numbers Server

I have been asked to use the ANU Quantum Random Numbers Service to create random numbers and use Random.rand only as a fallback.

 module QRandom

   def next
     RestClient.get('http://ift.tt/1AOlK3T'){ |response, request, result, &block|
       case response.code
         when 200
           _json=JSON.parse(response)
           if _json["success"]==true && _json["data"] 
             _json["data"].first || Random.rand(65535)
           else
             Random.rand(65535) #fallback
           end
         else
           puts response #log problem
           Random.rand(65535)   #fallback
       end
     }
   end

 end

Their API service gives me a number between 0-65535. In order to create a random for a bigger set, like a random number between 0-99999, I have to do the following:

(QRandom.next.to_f*(99999.to_f/65535)).round 

This strikes me as the wrong way of doing, since if I were to use a service (quantum or not) that creates numbers from 0-3 and transpose them into space of 0-9999 I have a choice of 4 numbers that I always get. How can I use the service that produces numbers between 0-65535 to create random numbers for a larger number set?