Wawa:
221ohm resistors do exist (E192, 0.5% or 0.2%), but they are as rare as hen's teeth.Seems that the writer of that article just copied the error on the resistor site.
Leo..
No, silly ... Mouser carries 434 221Ω resistor types:
...and the cheapest ones are a penny and a half at quantity 100!
...and available stock in the 10s of thousands!