In series 3 or 4........ But in parallel 30 or 50.... A
Right, but the more you put in parallel the quicker the batteries will drain.We need a lot more info for a proper answer.LED color, how long do you need these to run, how much space do you have to put this?
You can find how many LEDs you can run yourself using this online calculator.
That depends. You haven't given enough information to solve the problem. You don't specify how much current your LEDs draw. You don't specify how long you want them to stay lit. You haven't specified if you are going to connect them in parallel or in series, nor whether you are going to connect the batteries in parallel or in series.One AAA battery typically has about 1 A-hr of charge capacity. When you combine that information with the above parameters, you can compute how many LEDs you can use.