Certain things are made up, but other things aren't.
For example, a circle is 360 degrees. 360 degrees is just an arbitrary standard that was decided on. Why they chose 360 instead of 100, I don't know.
But on the other hand, pi is not made up. If you divide the circumference of a circle by its diameter (or 2 * the radius), you will ALWAYS recieve the number 'pi', which also appears in many other equations in mathmatics.
I read something yesterday that applies to this. Plato, ancient Greek philosopher, theorized that " mathematics is not created but discovered in some undescribed realm."
I agree with this, but also acknowledge that certain aspects of math (like the 360 degrees thing) are subject to interpretation.