You actually can't because you are simply defining a contract between the abstraction and a conctrete class which says the concrete class MUST implement the method, but it does not say anything about HOW it will be implemented. Therefor saying the method is going to comply with the IEE754 standard would not be right.
I'd like to point out that a question like this is easy to answer for yourself by simply trying the code with a compiler. This is stongly recommended as a tool for learning. Of course Marzo's answer is good for explaining why the compiler behaves this way.
Abstract methods cannot be marked as synchronized,strictfp, or native,all of which are modifiers describing something about the implementation of a method.bacause abstract methods define the signature,access, and return type,but can say nothing about implementation,following method declarations are illegal.