I think one must draw a distinction between the physical world and the metaphysical one. For a platonist, numbers do exist outside of any physical reality and, therefore, a number and its representation are not the same thing.

I am not a mathematician, but to me this discussion reminds me of a vector having different coordinates, depending on what coordinate system we choose. Those are all different representations of the same thing. Likewise, a number can be represented in many different ways (binary, oct, hex, etc), but they all represent the same number. Is the vector its representation? If so, then the vector is many things, which is a funny definition of "to be". If the vector is itself, then it cannot be equal to any of its representations, it's something beyond its representation.