What's the difference between rounding and truncating?

Rounding goes to the nearest value (3.146 → 3.15 at 2 dp), while truncating just drops the extra digits (3.146 → 3.14). Round up always increases, round down always decreases.

How does 'round half' work here?

We use standard round-half-up via Math.round, so 2.5 rounds to 3 and −2.5 rounds to −2 (toward +∞ at the half).

Rounding Calculator

Free rounding calculator. Enter a number and the decimal places to see it rounded to the nearest value, rounded up (ceiling), rounded down (floor) and truncated. Handy for math, finance and reports.

Round a number to any number of decimals — nearest, up, down or truncated.