It's a basic knowledge, but I'm confused and post a question.
I'm going to connect 10 LEDs in a bundle and connect them to one data pin of Arduino. In this case, is the resistance value is (resistance of LED * number of LED)?
For example, if the voltage of the Arduino is 5v, the voltage of the LED is 2v, and the current is 20ma, the resistance is 150 ohms. Then is it 1.5㏀ if I use 10 leds?
So 10 leds in parallel is 200mA, and that's way beyond what you can draw from a microprocessor pin.
So let's start over. You need more light than you get from a single LED. What's the application? Shall we try and look for a solution that may actually work, yes?
Yeah, but notice that OP seems to want to treat the LED as a resistor, which is what (s)he was talking about in the context of the 150R/1k5. This was not about the current limiting resistor.