What's a billion?

Madam, - I note from the business supplement (July 25th) the headline "Sales of Tysabri to tune of $200bn"

Madam, - I note from the business supplement (July 25th) the headline "Sales of Tysabri to tune of $200bn". Now that is a lot of money, roughly the same as Ireland's total GDP for 2006, according to a quick internet search.

So can we all retire early and live off the proceeds of what must truly be a wonder drug? No we cannot, as of course the headline involves a small mistake. That should be $200 million, as the text of the article makes clear. And, as luck would have it, on turning the page we get an idea of just how confusing such big numbers can be, as we see a picture of a $100 billion Zimbabwean bank note. As any Zimbabwean could tell us, those extra zeros on the end matter, they matter a lot.

To confuse matters even more, a billion in some countries still means a million million, as it did in Ireland until about 40 years ago. Now it means a mere thousand million. I have a suspicion myself that when most people read about something costing X billions they simply get a vague impression of "a lot of money". Might I suggest that in future a better convention would be to drop the word billion altogether, and instead spell it out in terms of thousands of millions. Thanks to the Lotto and spiralling house prices, we all now have a reasonable idea of just how much a million euro amounts to, in terms of what we could actually buy with it. - Yours, etc,

Prof MICHAEL SCOTT,

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School of Computing,

Dublin City University.