Dumb question about resistors in series/parallel

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Baby steps.  Take your time to understand how the series/parallel resistor thing works before diving into something more complex.

These are foundation skills that you need to be very comfortable with before stepping up, otherwise your uncertainty will turn to confusion and your confusion will turn to bewilderment.

For example, the network I put up above should take you less than 30 seconds to work out the equivalent resistance - just doing it in your head.  While real world examples are almost never so friendly, this example has carefully selected values that allow for very easy mental arithmetic.

There is, however, one shortcut that helps here: When you have 2 resistors of the same value in parallel, the equivalent resistance is half that of one.  With 3, it is one third; 4 = one quarter and so on.
eg.
Two 8 ohm resistors in parallel is 4 ohms
Three 24 ohm resistors in parallel is 8 ohms
Four 12,000 ohm resistors in parallel is 3,000 ohms

There are a couple of tricks you can use for some values that aren't equal - but for the most part, normal circuit calculations will have us pulling out the full formula.  So don't expect to be able to do every such problem without resorting to aids of some kind.