Rounding Calculator

Common rounding types: 1) Nearest Integer - rounds to whole number (3.7→4, 3.2→3). 2) Decimal Places - rounds to specific decimals (3.14159→3.14 for 2 places). 3) Significant Figures - counts all non-zero digits and zeros between/after them (0.00456→0.0046 for 2 sig figs). 4) Nearest 10/100/1000 - rounds to place value (347→350 for nearest 10). Used in: Science (sig figs), finance (2 decimals), measurements, estimates.

Standard rounding: If digit is 5 or more, round up. If less than 5, round down. Example: 2.5→3 (round up), 2.4→2 (round down). Banking/Banker's rounding (not in this calculator): Round 5 to nearest even number (2.5→2, 3.5→4) to reduce bias. Why 5 rounds up: It's equidistant, so convention rounds up for consistency. Financial calculators typically use standard rounding.

Sig figs rules: 1) All non-zero digits count (123 = 3 sig figs). 2) Zeros between non-zero digits count (1003 = 4 sig figs). 3) Leading zeros don't count (0.0045 = 2 sig figs). 4) Trailing zeros after decimal count (4.500 = 4 sig figs). 5) Trailing zeros in whole numbers without decimal don't count unless specified (1200 = 2 sig figs, but 1200. = 4). Used heavily in chemistry, physics, engineering for precision.

Decimal Places: Use for finance, money ($12.45 always 2 decimals), percentages, everyday measurements. Focuses on precision after decimal point. Significant Figures: Use for scientific calculations, measurements with different magnitudes, error propagation. Focuses on overall precision. Example: 0.00456 rounded to 2 decimals = 0.00 (useless), but 2 sig figs = 0.0046 (meaningful). Choose based on context: money/daily = decimals, science = sig figs.

Identify the place value, look at digit to the right. Examples: 347 to nearest 10: Look at ones (7). 7>=5, so round up → 350. 347 to nearest 100: Look at tens (4). 4<5, so round down → 300. 2,678 to nearest 1000: Look at hundreds (6). 6>=5, so round up → 3,000. Useful for: Estimates, population numbers (52,345 people ≈ 52,000), budgets, quick mental math.