# Question on the Definition of A Numeraire

I'm familiar with the idea of a numeraire when prices come in the form $$\frac{p_x}{p_y}$$, but I'm still trying to figure out what the more general notion of a numeraire is. For instance, if all that I'm given is $$p_x,p_y,$$ and $$m$$: what is supposed to be the numeraire there? Is it just 1 unit of currency?

numeraire is by definition some unit of measure by which we measure all other units. In your case, let us say that we would decide to use $$x$$ as a numeraire. In that case we would divide all prices by $$p_x$$ so the price for $$x$$ would become $$\frac{p_x}{p_x}=1$$ (one $$x$$ can be worth only itself) and for good $$y$$ the price would be set as $$\frac{p_y}{p_x}$$.