When we measure things and write down numbers to represent their height, weight, etc., we ALWAYS round. It means that we never say that somebody is 10 years and 4 months and 2 weeks and 3 days and 12 hours and 8 minutes and 9.32439284327497 seconds old. We normally just say that they are ten years old.

Age is a bit unusual though, because we truncate our number. Normally we don’t do this, but we round to the nearest number.

A number line is very useful to us in doing this. Let’s use the exercise below to familiarise ourselves with number lines. We can see from the number line where numbers should be rounded to based on their position. Let’s try this for a few, rounding to thenearest 10 or the nearest 100 or the nearest 1000.

Exercise

The logic is the same when we round to the nearest whole number or we round to one decimal place. Let’s try this with some examples before doing the exercise below.

Exercise