Microsoft Office Tutorials and References
In Depth Information
Writing your own formulae
When you select a group of cells, you can see the sum of their values, the
average value and the number of cells selected at the very bottom of the
screen. It only fl ashes up while the cells are selected, but it can be a quick
way to check a running total.
Writing your own formulae
Excel is capable of much more sophisticated formulae than you have discovered
in this project, and it can handle any calculations you can dream up for it.
I have two warnings, though. The fi rst is that although you can type a lot of your
working out into a cell, you probably shouldn’t. You could type your exchange
rate directly into a price formula, for example, and this might seem like a time
saver if you know you’re only using it once, but it makes it hard to see what’s
going on when you look at the spreadsheet. It’s better to make your workings as
transparent as possible, as I did with the exchange rate, by putting your numbers
into cells where you can see them, rather than having to dig around in formulae
to fi nd out what’s going on.
The second warning is that, when you’re creating complicated formulae,
sometimes you need to tell Excel which bits of it belong together to avoid errors. What’s
15 minus 5 times 2? It depends on whether you do the subtraction or the
multiplication fi rst. In Excel, you use brackets to show which bits belong together.
For example:
=15 - ( 5 * 2 )
=(15 - 5) * 2
The fi rst calculation gives the result 5 (5 times 2 is 10, and taken away from 15 that
leaves 5), and the second gives the result 20 (15 minus 5 is 10, times 2 is 20).
You’ll get an error if you don’t have the same number of opening and closing
brackets.
If your formula isn’t doing what you expect or is giving an error, it’s usually not too
hard to work out what’s gone wrong. Here’s a quick checklist that can help you
fi nd the problem more quickly:
 
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