100K ohm resistor, then a 10K ohm resistor, with the Arduino input coming from between them. 3. My Arduino recorder consistenly measures voltage 5% higher than what the multimeter reads.
it would be about 300 ohms
A breadboard may not be the most reliable connection, but generally it does not add 300 ohms of resistance. In practice it should not add more than .01 ohm of resistance (my estimate only).Use your volt meter, and read the voltage from your voltage divider (at the analog input pin). Then do the math. What do you get?