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To round...

• Decide how many digits you want to keep.
  (how many "significant figures").

  Examples...	You could round	24314
  	to 4 significant figures:	24310
  	to 3 significant figures:	24300
  	to 2 significant figures:	24000
  	to 1 significant figure:	20000

  
  If you don't want any at all, see Rounding to an order of magnitude.
  (Then you round up from 3 rather than 5).

• Then round away the rest. (round up from 5)

  Round up when the first digit being rounded away is 5 or bigger.
  

  Only that single digit matters.
  24999 rounded to one place is 20000, not 30000.
  The 4 is less than 5, so we don't round up.
  The 9's don't matter. They can't make a 4 into a 5.

  Examples...	835049	can be rounded to
  	835050	(5 significant figures, the 9 rounds up the 83504 to 83505)
  	835000	(4 significant figures, the 4 doesn't)
  	835000	(3 significant figures, the 0 doesn't)
  	840000	(2 significant figures, the 5 rounds up the 83 to 84)
  	800000	(1 significant figure, the 3 doesn't).
  	1000000	(No significant figures, order of magnitude).

• You're done.