Question 1

How do you round a number?

Accepted Answer

Standard rounding (round half up): look at the digit immediately after your target place. If it is 5 or more, round up; if less than 5, round down. Round 3.456 to 2 decimal places: look at third decimal (6 ≥ 5) → round up → 3.46. Round 3.454: look at third decimal (4 < 5) → round down → 3.45.

Question 2

What is banker's rounding (round half to even)?

Accepted Answer

Banker's rounding rounds 0.5 to the nearest even number: 2.5 → 2, 3.5 → 4, 4.5 → 4, 5.5 → 6. Standard rounding always rounds 0.5 up (2.5 → 3). Banker's rounding is used in financial calculations to eliminate cumulative upward bias when always rounding 0.5 up over many transactions.

Question 3

What is the difference between floor and ceiling?

Accepted Answer

Floor rounds down to the nearest integer: floor(3.7) = 3; floor(−3.7) = −4. Ceiling rounds up to the nearest integer: ceiling(3.2) = 4; ceiling(−3.2) = −3. Truncation (round toward zero) differs from floor for negatives: truncate(−3.7) = −3.

Question 4

How do I round to significant figures?

Accepted Answer

Significant figures (sig figs) count meaningful digits from the first non-zero digit. To round 0.003456 to 2 sig figs: first non-zero digit is 3 at 4th decimal place; round to 2 sig figs from there → 0.0035. To round 12,345 to 3 sig figs: 12,300.

Question 5

When should I use different rounding methods?

Accepted Answer

Standard (round half up): everyday math, schoolwork. Banker's rounding: financial reporting, statistics (reduces cumulative bias). Floor: inventory allocation (can't give half a unit). Ceiling: safety margins, time estimation (always round up to ensure enough resources). Truncation: integer conversion in programming.

Rounding Calculator