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Biggest number in the world
By WATTSIE on March 10, 1998:

What is the biggest number in the world ever found?

By Anonymous:

Dear WATTSIE,

That's an interesting question. The strictly correct answer is: there is NO biggest number in the world. Whatever number you think of, however big, I can add one to it (or 2 or 10, or whatever I want) and get a bigger number. If you think that one is then the biggest, just add one again, and you get a bigger one! We say that the numbers are INFINITE - this means that they `go on for ever', and you can never reach the end, however far you count. The opposite of infinite is FINITE - this means that you can count how many you have and the counting process will stop. For example, the number of hands I have is finite since I can count up to 2 and then I can stop counting.

However, a more interesting question is: what is the biggest USEFUL number that has been found?

What do I mean by `useful'?

Possible answers to this question are: the number of something in the universe. For example, there estimated to be about 1080 particles (very small bits of matter) in the universe. That means 1 followed by 80 zeros - a VERY big number! (Please tell me if you don't know what powers are.)

But this number really isn't all that big. What about the number 101080 - this is 1, followed by 1080 zeros. This really is unbelievably big.

The biggest known prime number (again, tell me if you don't know what a prime number is), is 22976221 - 1. This is also pretty big, but very much smaller than the last number I wrote down.

The biggest number you can write with 3 digits is 999 (write this as a tower of 9's and it doesn't use any symbols). If you know about logarithms, they are a good way of working out how big all these numbers are relative to each other.

An even bigger number is one called "Skewes' number". It turns up in a theorem (an important result) that somebody proved this century, which has to do with how many prime numbers there are below a certain number. It is 10101034. This is VERY MUCH BIGGER than that very big number I wrote down before! And yet it comes into the proof as the biggest number below which something must happen. (In fact, an approximation changes from being below the right answer to above the right answer, or maybe it's the other way round, I don't quite remember.)

There is also a number called Graham's number which is ridiculously huge.

If you want to find out more about very big numbers, and lots of other numbers, there is a very good book called `The Penguin Book of Curious and Interesting Numbers'. It has lots of information about lots of different numbers, including the ones above (although you won't find out about the prime I told you about, because that was discovered very recently, over the Internet in fact. See the web-site http://pass.maths.org.uk/issue3/news/prime.html.

I hope you've found this interesting and useful!

David.

By The Editor:

Two larger primes than the one mentioned above have been discovered, and I'm sure there are more to come. The following link should give you up-to-date information:
The Largest Known Primes