To run an Arduino you need either 5V regulated , or higher if you want to use the onboard regulator
on the Arduino board.
So you need at least 4 1.5 V AA batteries in series , or 5 1.2 V in series.
Even thats a bit marginal for the onboard voltage regulator.
Maurid - Thanks again for the input. I have few other questions related based on your feedback:
1- Would I not be in a better position to use a 9V battery then than AAs?
2- I assume that regulated needs extra equipment and I want to stay from that. Does the onboard regulator allow a 9v battery to connect to it or any other battery like AA to connect to directly with a simple wire?
3- I assume I am better off with a Lithium-ion battery of all options above. If so, what type of Lipo battery best works with Arduino?
4- How would my situation be different if I were to use an Arduino Nano?