I usually use a 250 ohm resistor to measure a loop that I don't want to break to get in sereies with. Of course you use ohms law to obtain the resistor value. I use that resistor as a regular "tool".
Current stay the same in series. Voltage stays the same in parallel. It really isn't a "stupid" question. You would be suprised how many rookies right out of school do not know this.