Rounding Calculator

1. Enter a number. It can be a decimal like 3.14159 or an integer like 12345.
2. Set the decimal places with the slider (0 to 10). The default is 2.
3. Read the results. Standard rounding uses the "round half up" rule. Ceiling always rounds toward positive infinity. Floor always rounds toward negative infinity.
4. Check the comparison table to see all rounding methods at multiple precision levels at once.

Standard (half-up rounding):
  If digit after cutoff >= 5, round up. Otherwise round down.
  3.14159 to 2 places: look at 3rd decimal (1). 1 < 5, so round down: 3.14
  3.14559 to 2 places: look at 3rd decimal (5). 5 >= 5, so round up: 3.15

Ceiling (always round up toward +infinity):
  3.14159 → 3.15 (to 2 places)
  -3.14159 → -3.14 (toward +infinity)

Floor (always round down toward -infinity):
  3.14159 → 3.14 (to 2 places)
  -3.14159 → -3.15 (toward -infinity)

Significant Figures:
  Count digits starting from the first non-zero digit.
  3.14159 to 3 sig figs: 3.14
  0.00543 to 2 sig figs: 0.0054
  12345 to 3 sig figs: 12300