pos neg doesnt matter with OHMs.
12.5 to 8.7 what? or is it just 12.7 ohms?
If it is just 12.7 Ohms, put your meter to the lowest setting that prevents the measurement from going over, kinda like the price is right. So in your case, 200 OHMS is the lowest becasue you will never be able to read 12 ohms in a 2000 scale using an analog meter.
Is your meter digital, or analog? I am guessing digital and has 3 or four places on the screen with one number to the right of thedecimal point.

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