As promised in my original "
birthday math" post, I am now going to analyze Keziah's birthday (12-28). I have to admit I was at first disappointed in this birthday from a mathematical standpoint. Of course I was super happy about when she came for a dozen other reasons so I did not complain. But looking at 12 and 28 the only cool thing I could really come up with was that they were both divisible by 4 leaving 3 and 7 which are Biblical numbers symbolizing completeness. And this is symbolic for us too as I feel our family is somewhat "complete" now that we have a child (that's not to say we are "one and done" or anything - but just feel more complete now than before is all). So that was kinda cool. But other than that, I really struggled for anything more. 12 and 28 - they weren't perfect squares or cubes. And they didn't make a palindrome or nice equation. Then I stopped looking at the numbers 12 and 28 and looked at the individual digits 1, 2 and 8. The first thing I thought of was obviously that 1 doubled is 2 and 2 cubed is 8. I liked that. But then it hit me that 1, 2 and 8 are all Fibonacci numbers. Now I was finally satisfied. This I like. It ties perfectly into my obsession with the golden mean. Here is a picture of Keziah's nursery wall:

I constructed the golden rectangle with the golden spiral a while back but since we didn't know what we were having, the name hanging in the spiral is a recent addition. Since most of you reading this probably don't care about the math behind the golden mean as much as I do, I'll spare you the long lecture (although the teacher in me would really like to get into it). If you want to learn more click
here. I'll sum up how this ties into her birthday. The golden mean is a wonderful ratio that happens to be (1 + squareroot of 5) : 2. The golden rectangle is simply a rectangle whose length and width are in this ratio. (You can construct one with just a compass and straight edge which is how I got it on the wall.) Any time you cut off a square in the rectangle, the resulting rectangle is another golden one. So you can do this ad-infinitum. And if you construct the arcs in all these squares you get the logarithmic spiral known as the golden spiral. So how does this tie into Fibonacci numbers? The Fibonacci Sequence is the sequence of numbers you get by starting with 1 and 1 and then always adding the two previous numbers to get the next one (1,1,2,3,5,8,13,21,34......) Now here is a cool fact: The limit as n approaches infinity of F sub n+1 divided by F sub n is equal to the golden mean. Or to put it in non-mathy language, the ratio of two consecutive Fibonacci numbers approaches the golden ratio the further you get along in the sequence. (There are other connections but that is the simplest one.) Voila! Is that not just the coolest thing ever? So my little one has a "golden" birthday! I'll conclude this post with a picture of my sleeping Keziah with her "bibonacci" bib on that Aunt Julie gave her. (Yes there are enough of us math dorks out there having kids that some company thought to make this.) Do you get the humor?
