Hey guys, I am completely new to Arduino, and calculating/using resistors in general...

As I understand it, the Arduino Uno's Digital Output pins are 5V, correct? I have a 3V Buzzer I want to power. Since I don't want to blow the buzzer, I should use a resistor, right?

Ohm's law is V=I*R, but this is where I am stuck. Do I use 5 for V, or 3?

I think it would be either a 200 or 300 Ohm resistor, but I'm not sure. Could somebody please explain, in detail, how to calculate this?

Thanks!