What is rounding and why do we do it?

  • Rounding a number means changing a number to a similar amount in order to make it simpler. This can make it easier to calculate with or use in everyday life.

Example 1

You might decide to round 365ml down to 350ml when measuring water for a recipe.

A measureing jug

Example 2

This calculation might seem difficult:

5.497586986976 x 2

By rounding the long number to 5.5 the (approximate) answer feels simpler to work out:

5.5 x 2

Be mindful! Rounding will make the number less accurate. Whether this matters or not depends on what it is being used for.