There is a question on the GCSE paper that asks about measurements, and asks for the possible range if you are told that it is correct to the nearest metre. So if the question gives you a figure of 754 metres, the lowest possible measurement is 753.5 metres. If you are told that the measurement is to the nearest centimetre they will probably give you a number in centimetres, say 937, and the lowest answer is then 936.5 centimetres. Don't forget units as they are important as I mentioned yesterday.

The next question is about areas. If you are given an area in square metres can you convert it to square centimetres. If you picture a metre in lenth then make this is one side of a square and you have a square metre. If you picture a length of 10 metres and make this one side of a square then you have 10 metres squared and you can fit 100 square metres into it. 10 metres squared = 100 square metres. It's the same with any unit of length.

To make it a little more difficult you are given 2.2 kilometres squared and you are asked to work out the number of square metres. The first thing to do is make the units the same. It will work either way but you have been asked to give your answer in terms of metres, so work in metres. 2.2 kilometres squared is 2 200 metres squared. Now imagine a length of 2 200 metres and then make a square of it. You have 2 200 x 2 200 square metres = 4 840 000 square metres. It shows that you know the difference between square metres and metres squared, and also that you can multiply big numbers together.

That sums it up.

## Saturday, 11 April 2009

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