[SOLVED] Finding the unknown resistor using only an ohmmeter In a box there are 12 resistors, 11 of them have a resistance of exactly 1 ohm, and 1 of them doesn't. Using only an ohmmeter, what's the least measurements you can make to find out which one is the odd resistor and what's its value? (You can't count on luck!) Equations: For resistors in series: R(equivalent) = R1+R2+R3+... For resistors in parallel: 1/R(equivalent)=1/R1+1/R2+1/R3+... I got to 5 by deviding them up into 2 sets of 6, then measuring the resistance of each one (2 measurements). That would give me R. Then I would get 2 groups of 3 and measure one of them (3 measurements). If I get 3 ohm I know the odd resistor is in the other group. Then I measure the resistance of 2 of the 3 and finally find the odd one (5 measurements). I'm pretty sure there's a better way... and I think I should be playing with the series/parallel concept, but I couldn't find anything better than 5... Any ideas?