Choose a Rounding Rule Before Rounding
Zero decimal places rounds to a whole number.
Decide which place matters
Zero decimal places rounds to a whole number. Two places rounds to hundredths. A place count of -2 rounds to hundreds, so 1,249 becomes 1,200 with nearest rounding. The place count is not a count of significant figures.
Check the halfway convention
Nearest rounding needs a rule for a value exactly between two choices. This tool uses halfway away from zero: 2.5 becomes 3 and -2.5 becomes -3 at zero decimal places. Other systems may use ties-to-even.
Compare floor and ceiling
Floor is the greatest integer no larger than the value; ceiling is the smallest integer no smaller. At zero places, -3.2 has a floor of -4 and a ceiling of -3. Simply deleting digits would not reproduce both operations.
Round at the right stage
Repeated intermediate rounding can accumulate differences. Keep adequate precision while calculating and apply the required final rule afterward. For an invoice or a specified reporting system, follow its documented decimal and rounding policy.
Put it into practice
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Round to decimal places or powers of ten, with explicit nearest, floor and ceiling rules.
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