Before solving a real-world circuit problem, it is helpful to recall the core principles for analyzing resistors in series and parallel, as well as how current divides in such circuits. When resistors are in series, their resistances simply add: the total resistance is the sum of the individual resistances. For resistors in parallel, the reciprocal of the total resistance equals the sum of the reciprocals of each resistor's resistance. Current division principles tell you that in parallel branches, the current splits inversely proportional to the resistance of each branch, while in series the current is the same through all resistors. These foundational concepts allow you to analyze more complex circuits by breaking them down into simpler series and parallel combinations.