Name what is the number halfway between 500 and 800?

Halfway between means if we put the two numbers on the number line, we find the distance between the two numbers and if we go half that distance we get to the number we are looking for.

Now the distance between 500 and 800 is 800-500 or 300.
We need half of that which is 150. So now take 500+150=650 or take 800-150 which must also be 650.