| Round to nearest | Result |
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Rounding replaces a number with a shorter one that is close to it. Decimal places count digits after the point (3.14159 to 2 places is 3.14); a negative count rounds to tens, hundreds and so on (1234 to -2 places is 1200). Significant figures count from the first non-zero digit, so 0.004567 to 2 significant figures is 0.0046. The calculation works on the exact digits you type, so 1.005 rounds to 1.01 as expected and there are no floating-point surprises. Trailing zeros are kept because they show the precision.
Look at the hundredths digit. If it is 5 or more, raise the tenths digit by one; otherwise leave it. So 7.46 becomes 7.5 and 7.44 becomes 7.4. The table above shows every common place at once.
Also called round half to even: a value exactly halfway rounds to the nearest even digit, so 2.5 becomes 2 and 3.5 becomes 4. It avoids a small upward bias when rounding many numbers and is used by many programming languages and accounting rules.
Count every digit from the first non-zero digit onward. 0.00450 has three (4, 5, 0) and 1200 is usually treated as two unless the zeros are marked as measured.
See also: scientific notation converter · decimal to fraction converter · percentage calculator