GCD and LCM Calculator
Calculate GCD (greatest common divisor) and LCM (least common multiple) of two numbers. Free online calculator.
Current for 2026Methodology →
Rounding calculator
Enter any number and choose your rounding precision — from 3 decimal places to the nearest thousand. The calculator uses standard mathematical rounding (round half up) and shows the difference between the original and the rounded value. Useful in finance, science, school and everyday calculations.
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How we round numbers
Rounding to d decimal places: result = Math.round(x × 10^d) / 10^d. To tens: Math.round(x / 10) × 10. To hundreds: Math.round(x / 100) × 100. Digit 5 always rounds up (round half up). Error = |result − original|.
Example calculation
3.14159 rounded to 2 decimal places: the third decimal is 1 (< 5), so the result is 3.14. Rounding error: 0.00159. Rounded to the nearest whole number: 3 (first decimal = 1 < 5).
Frequently asked questions
How do you round to 2 decimal places?
Look at the third decimal digit. If it is 5 or more, the second decimal increases by 1; otherwise it stays. Example: 3.14159 → 3.14.
How do you round to the nearest whole number?
Look at the first decimal digit. If it is 5 or more, add 1 to the integer part; otherwise drop the decimal. Example: 7.5 → 8, 7.4 → 7.
How do you round to the nearest ten?
Look at the units digit. If it is 5 or more, add 10 and zero the units; otherwise just zero the units. Example: 46 → 50, 44 → 40.
How do you round to the nearest hundred?
Look at the tens digit. If it is 5 or more, add 100 and zero the tens and units; otherwise just zero them. Example: 350 → 400, 349 → 300.
Which rounding method does this calculator use?
Round half up — a digit of 5 always rounds away from zero. This is the standard method taught in schools and used in most calculators.
Why is rounding to 2 decimal places important in finance?
Monetary values are expressed to the nearest cent (2 decimal places). Incorrect rounding can cause errors in invoices, taxes and interest calculations.
Can negative numbers be rounded?
Yes. The same rules apply: digit 5 rounds away from zero. Example: −2.555 rounded to 2 places → −2.56.
What is the difference between rounding and truncation?
Rounding considers the value of the discarded digits; truncation simply drops them. Example: 3.99 rounded to 1 place → 4.0, truncated → 3.9.
How many decimal places does this calculator support?
You can round to 1, 2 or 3 decimal places, or to the nearest whole number, ten, hundred or thousand.
How do I round a percentage result?
After calculating a percentage (e.g. 17% of 123 = 20.91), enter the result as the input number and choose your desired precision.
The result is indicative. The calculator uses round-half-up — other rounding methods may give different results.