Monday, May 23, 2005

In my prime

When I was in 7th grade, I got a calculator watch. The combination of a calculator watch and not such an active social life, together with my constant need to gadget (is that a verb?) led me into the interesting world of fractions. I would take the number 1, divide it by some other number, and find out what repeats. Some of these are easy, like 1/3 = .3333~. I also found that 1/7 = .142857~.

All of this is because 1 = .999~ (It really does. Trust Cecil.) So as long as a number consisting of 9's can be divided by some other number, it will eventually repeat. This page explains the idea pretty well.

Looking at numbers this way shows a real beauty that is found in the simplicity of the world. All this from a Casio.

My affection for composite numbers (the opposite of prime numbers) showed up later in life as well. When the Israeli phone company introduced two new features - one that calls back the number that last called you, the other that continues calling a busy number - I had trouble remembering which was which. The first was *42, the second *41, but I kept mixing them up. But then I remembered that *41 is known here as nudnik - and what's more annoying than a prime number? 41 can't be divided by anything! (I'm sure Hitchhiker fans could make a 42 association, but this was easier for me.) Might sound silly, but I haven't forgotten it since...