Understanding Rounding
Rounding is a process of replacing a number with a simpler value that is approximately equal to the original. This is used to make numbers easier to work with or to reflect the precision of a measurement.
Significant Figures
Used in science to indicate precision. Non-zero digits are always significant. Zeros between non-zeros are significant. Leading zeros are never significant.
Decimal Places
Common in finance (usually 2 places for cents). It refers to the number of digits to the right of the decimal point.
Rounding Strategies
How you handle the "halfway" point (0.5) depends on the strategy used:
The standard school method. 0.5 rounds up to the next integer.
Rounds to the nearest even digit. Used in finance to reduce cumulative bias.
Always rounds toward positive infinity.
Always rounds toward negative infinity.
Rounding Examples Reference
| Original | Target | Result | Diff |
|---|---|---|---|
| 123.456 | 2 Decimals | 123.46 | +0.004 |
| 123.456 | 0 Decimals | 123 | -0.456 |
| 123.456 | 2 Sig Figs | 120 | -3.456 |
| 2.5 | Banker's (0 Dec) | 2 | -0.5 |
| 3.5 | Banker's (0 Dec) | 4 | +0.5 |
| 17.3 | Nearest 5 | 15 | -2.3 |