Sunday 1 March 2009

How to work out powers

Following on from yesterday's idea of the chessboard, you know that 8x8=64 and you can picture it as a square. It is eight squared or in other words 8 to the power 2 is 64. You say eight to the power two because there are two eights. If you multiply 10x10 you get 100. 10 to the power 2 is 100. 10x10x10= 1 000 and is 10 to the power 3. There is a sequence here and 10 to the power x (where x is any number) has x number of zeros after the one.

If you take one step backwards in this sequence from 10 to the power 2, you have to divide by 10. You get 10 to the power 1. And any number to the power 1 is that number itself. 10 to the power one is 10.

Take one further step backwards and you get ten to the power zero. When you divide 10 by 10 you get one. Any number to the power zero is 1 (it is that number divided by itself), e.g. four to the power zero is one.

The next step backwards is 10 to the power minus one. The sequence continues and you divide by 10. Any number to the power minus one puts that number in the denominator so ten to the power minus one is one tenth. Four to the power minus one is a quarter.

That sums it up

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