What is rounding?

Rounding is a way of simplifying numbers. If the driveway of a house is 5 metres and 7 cm long we would usually just say it is 5 m long.
Saying it's 5 m long will be close enough most of the time.

Here is another example. The picture shows a stick of rock next to a ruler. The ruler has only got the 10 cm points marked on it.

We can't see exactly how long the rock is. But we can see to the nearest 10 cm. The end of the rock is close to the 20 cm mark. So we say that the rock is 20 cm long to the nearest 10 cm.

What about this longer stick. How long is it to the nearest 10 cm?

It is closer to 30 cm than 20 cm. So we say it is 30 cm long to the nearest 10 cm.

Rounding numbers to the nearest 10 means finding which 10 they are nearest to.
Rounding a number to the nearest hundred or to the nearest thousand can be done in the same kind of way. There is more about this in the other factsheets.