Rounding to 1 decimal place

Topic guide

What this worksheet practises

This worksheet focuses on rounding numbers to 1 decimal place. This is the most common form of rounding in everyday life, often used for measurements like weight (e.g., 74.3 kg) or distance (e.g., 5.2 km).

Key method

When rounding to decimal places, you start counting immediately after the decimal point, ignoring everything in front of it.

• Locate the decimal point.
• Look at the very first digit immediately after the point. This is the 1st decimal place.
• Look at the single digit immediately to its right (the 2nd decimal place). This is your "decider".
• If the decider is 5 or more, round your 1st decimal place up by one.
• If the decider is 4 or less, keep your 1st decimal place the same.
• Write out the full number, stopping exactly after your 1st decimal place digit. Drop all the numbers that come after it.

Worked example

Round 14.839 to 1 decimal place.

Step 1: Find the 1st decimal place. It is the 8.

Step 2: Look at the decider to its right. It is a 3.

Step 3: Because 3 is less than 5, the 8 stays exactly as it is.

Step 4: Write the number, stopping after the 8. Drop the 3 and the 9.

The final answer is 14.8.

Common mistakes to avoid

A common error is looking at the very end of the number to decide how to round. In the example 14.839, a student might see the 9 at the end, use it to round the 3 up to a 4, and then use that 4 to decide the fate of the 8. This "chain rounding" is completely wrong. You only ever look at the single digit immediately next to your target. The 9 is entirely irrelevant.

Things to remember

If you are asked to round 14.96 to 1 decimal place, the decider is 6, so the 9 must round up to 10. The 1 carries over the decimal point, making the 14 a 15. The correct answer is written as 15.0. You must include the ".0" to prove you have rounded to exactly 1 decimal place.