Rounding

For grown-ups: this lesson in words

Years 4 to 6 · Maths

Rounding: I can round numbers and use rounding to estimate.

1. Rounding changes a number to the nearest 10. Here is 37 on a number line from 30 to 40.

   30 is 7 away.

   40 is only 3 away. 40 is nearer.

   So 37 rounded to the nearest 10 is 40.

   Picture: A number line from 30 to 40. A dot at 37 labelled "37". The frog makes 2 hops: 37 to 30 (7 back) and 37 to 40 (3 on).

2. Here is a quick way. To round to the nearest 10, look at the ones digit.

   37 has 7 ones. 7 is 5 or more, so we round up to 40.

   Picture: A place value chart showing 37: 3 tens and 7 ones. The ones column is highlighted.

3. Here is 32. Its ones digit is 2.

   2 is 4 or less, so we round down. 32 rounded to the nearest 10 is 30.

   Picture: A place value chart showing 32: 3 tens and 2 ones. The ones column is highlighted.

4. Your turn: Round 52 to the nearest 10.

   Picture: A number line from 50 to 60. A dot at 52 labelled "52".

   Choose one:

   • 50
   • 52
   • 60

   Answer

   The answer: 50

   52 has 2 ones. 2 is less than 5, so round down to 50.

   Picture: A number line from 50 to 60. A dot at 52 labelled "52". The frog hops from 52 to 50 (2 back).

Words to know

round:

Change a number to the nearest tidy number, such as the nearest 10.

nearest:

The closest one.

halfway:

Exactly in the middle of two numbers. Halfway always rounds up.

estimate:

A sensible guess at an answer, made by rounding first.