@nlbucki
Please keep your threads together. Start a topic, and stick with it.
You want 10 groups of 5 LEDs each.
Use your transistor idea and arrange the LEDs like this:
I've included the voltages and suggested currents. Tweak as you like & solve for resistor values.
For 2 LEDs: (9-1.85-1.85)/.02 = 265 ohm. Use a 270.
Resistor power: P = IIR, so 20mA * 20mA * 270 as an example = 108mW.
So a 250mW resistor (1/4 W) would be just fine.
