# 143

Today is the 143rd day of the year.

When I look at the number 143, my mind immediately converts it to 11×13 (which you can see right away if you write 143 as 130 + 13). And then my mind starts to wonder “what fun things can I do with this?”

Which brings me back to a math epiphany I had when I was twelve years old. It was the first time I’d ever gotten a chance to program a computer, and our teacher said we could write a program to do whatever we wanted.

Being a typical American kid, the first thing I thought of was to find a fraction B/A that was really close to π.

So I wrote a program that tried all values of A up to a thousand. For each of those, my program tried all values for B that were about three times bigger than A. Then I checked to see how near B/A was to π.

To my great surprise, one fraction was vastly more accurate than all the others: 355/113. This fraction gets amazingly close to π — to around one part in four million.

What made this especially cool was how easy it was to remember. I just needed to write “113355”, then chop in the middle to get the A and B for my fraction.

I found out later that this marvelous approximation to π was first discovered in China, by Tsu Ch’ung-Chih, around 1600 years ago. Unlike me, he managed to find it without a computer.

## One thought on “143”

1. Hitoshi Yamauchi says:

and today,144=12^2. The next of 11×13. First I thought such a coincidence. But, an hour later (I’m getting really old), I realized that x^2-1=(x+1)(x-1). Now I cannot wait how I call tell my students on Monday without algebra, since they are 8 to 10 years old.