Series Resistance

The total resistance of n resistors in series equals the sum of each resistor.

R_{total}=R_{1}+R_{2}+R_{n}

R_{1}=R_{total}-R_{2}-R_{n}

R_{2}=R_{total}-R_{1}-R_{n}

etc.

More info: http://en.wikipedia.org/wiki/Series_and_parallel_circuits#Resistors