In SX Microcontrollers, SX/B Compiler and SX-Key Tool, JonnyMac wrote:

With 470-ohm resistors you should get about 3.8 or so milliamps through your LEDs -- probably won't be very bright.  The formula is pretty easy:

iLed = (Vsource - Vled) / Rlimiter

so...

(5.0 - 3.2) / 470 = 0.0038

If you wanted to get 10 mA through the LEDs you can do that by dropping to a 180 ohm resistor.  Since you're just getting started, let me recommend you get a copy of the Forrest M. Mims book, "Getting Started In Electronics" -- it will be a very big help as you move forward with your experiments.

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