@guigus,
You are a confusing individual at times... The hint would imply a mathematical equation which would lead me to assume, initially, that you are referring to the numerical digit "fifteen". That however doesn't really answer the question as to your "meaning" towards that numerical digit, if that's, in fact, what you are referring to. Are you specifically referring to just the numerical digit? It would actually seem as though you're trying to make the point that our "meanings" about "fifteen" can be the same...although that would change the entire meaning of fifteen (in this situation) for you. The reason being, is that you would just be using fifteen as a tool (rather than a numerical digit) with a motive behind it, thus intertwining "fifteen" with that motive to create some new "meaning" for "fifteen".
Even if you were only referring to the numeric digit without any kind of point to it, we could still delve deeper into context about "fifteen" and the equation 14+1 and find differences there. For example, fifteen may be a simple numeric digit for you, and 14+1 just a simple mathematical equation. For me, "fifteen" represents my age in a very important event in my life, and "14+1" represents the number of extended family that I know of (the 14) and the (1), being myself.
The point I'm making in all of this is that we can come to perfect agreement in anything that is stated without specifics, but the more specific that you get, the more the differences in our "meanings" show. Those differences are what make us unique however and by providing the context around and about that, we help to convey ourselfs to each other to form relationships and to build understanding.