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Rounding Calculator

Free online tool that helps you round a given number to a specified number of decimal places or whole number places.


What is the precision of a number?

The precision of a number refers to the level of detail or accuracy with which it is expressed or measured. It is typically determined by the number of digits used to represent the number.

For example, the number 3.14159265359 is more precise than the number 3.14 because it includes more digits after the decimal point. Similarly, the number 1000 is less precise than the number 1000.0 because it does not include any decimal places.

In some contexts, precision can refer to the smallest unit of measurement or the smallest increment that can be detected or measured. For example, a ruler with millimeter markings is more precise than a ruler with centimeter markings because it allows for measurements to be made to a smaller increment.

The level of precision required depends on the specific application or problem being solved. In some cases, a high level of precision is necessary to ensure accuracy and reliability, while in other cases, a lower level of precision may be sufficient.

How to round a number?

To round a number, follow these steps:

  1. Determine the place value you want to round to (i.e., the digit to the right of the digit you want to round).
  2. Look at the digit in that place value. If it is 0, 1, 2, 3, or 4, round down (keep the original digit). If it is 5, 6, 7, 8, or 9, round up (increase the original digit by 1).
  3. Replace all the digits to the right of the one you rounded with zeros.


  • Round 3.14159 to two decimal places:

    The digit in the third decimal place is 1, which is less than 5, so we round down. Therefore, the rounded number is 3.14.

  • Round 6.987654321 to three decimal places:

    The digit in the fourth decimal place is 6, which is greater than 5, so we round up. Therefore, the rounded number is 6.988.

  • Round 123.456789 to the nearest integer:

    The digit in the ones place is 3, which is less than 5, so we round down. Therefore, the rounded number is 123.

Note: There are different rounding methods depending on the context and purpose of rounding. The method described above is the most common method called "rounding to the nearest" or "conventional rounding".