STANDARD RESISTOR VALUES
========================
Multipliers: 1 10 100 1,000 etc.

  MAIN		SECONDARY
 SERIES		 SERIES

  10		   11
  12		   13
  15		   16
  18		   20
  22		   24
  27		   30
  33		   36
  39		   43
  47		   51
  56		   62
  68		   75
  82		   91

Thus, 1.8 ohms, 18ohms, 180kohms, etc. are standard values.

Note that the main series is less expensive and more widely available.