Yes, that's true.
In fact, when n resistors are connected in series, their equivalent resistance is the sum of the resistances of all the resistor:
[tex]R_{eq} = R_1 + R_2 + ... +R_n[/tex]
Therefore, we immediately see from this formula that [tex]R_{eq}[/tex] is always larger than the value of the resistance of any single resistor in the formula.
