How do find the difference in distance from northings and eastings?

Question

I want to find out how far away two points are by subtracting northings and eastings.

Answer 1

You have to know what map units (feet/meters) your projection uses, then subtract and use the Pythagorean Theorem (a^2 + b^2 = c^2) where a and b are your differences and c is your distance (hypotenuse).