In an electric circuit three resistors of capacity 1Ω, 2Ω and 3Ω are connected in series. Their equivalent resistance will be :

When the resistors are placed in series connection then the net or total resistance can be evaluated by simply adding all the resistances in series like we add positive integer numbers.

But the total resistance will be 1Ω+2Ω+3Ω = 6Ω, which is the net resistance of the circuit.