How do I determine odd or even when working with altitudes? I am always confused about how to calculate safety altitude, especially when it comes to even heights and odd heights, e.g. is 7500ft even or odd?
Look at the thousands of feet only.
Is 7(thousand) even or odd?

I'm sure a mathematician views 7,500 as equally close to 8,000 as 7,000.

But in aviation terms, it is 7,000 plus another 500 feet, and therefore an odd altitude.