An amusing coincidence is occurring today and it relates to a beautiful set of numbers dating back to the 12th century.
The Fibonacci sequence is named after Italian mathematician Leonardo Fibonacci.
His 1202 composition, Liber Abaci, introduced the sequence to Western European mathematics.
And for those who use the Gregorian calendar, as Australia does, August the 5th, 2013, is a symbolic date for Fibonacci aficionados.
Peggy Giakoumelos has the details.
"The Fibonacci sequence has long been studied by mathematicians because it's really quite an elegant sequence. You achieve this sequence of numbers by simply adding the two numbers you've got and that generates the next one, and then you add that to the one you just had and it keeps growing like that. August the 5th is the 5th day of the 8th month of the 13th year of the 21st century, so we have the sequence 5,8,13,21 and that is part of the sequence of the Fibonacci sequence."
That's Doctor Ian Skinner, from the University of New South Wales, explaining how this date relates to the Fibonacci sequence.
Born Leonardo Fibonacci, the 12th century mathematician is better known simply as Fibonacci.
He's best known for spreading the Hindu-Arabic numeral system in Europe through his book Liber Abaci, or the Book of Calculation.
As for a practical application of his sequence, he put it to use by investigating how fast rabbits could breed in ideal circumstances.
Dr Skinner explains.
"It first entered the literature of Western Europe when Fibonacci was trying to estimate how many rabbits he would have in any given month by adding up the number of rabbits he'd had a couple of months before, and the number of rabbits he had in the month currently, and then projecting forward how many rabbits would be born in the month coming along."
Dr Marcel Jackson is a mathematician at La Trobe University.
He says whether this is the last time the Fibonacci sequence appear within the Gregorian calendar is unknown.
And, like the construction of the calendar itself, the application of the sequence is subject to a number of arbitrary factors.
"I guess it depends on what pattern you're looking for. I mean if you're looking for 5, 8, 13 which I am guessing is the secret pattern which is bringing this to some people's attention, I suppose you are not going to get something with a number 13 in the month, but you have to take into account that we're already ignoring the 20 part of 2013 fairly arbitrarily I would say. But then of course the whole calendar is set up vaguely arbitrarily, something that's just evolved through history which we all know there's some quirks to it. I mean there is a lot of maths associated with the construction of calendars, but as for the precise lengths of the month, really a bunch of historical anomalies which give rise to things like February being quite as short as it is and things like that. So all of those are what determine our current date. It would be very surprising if somehow a particular pattern that can be constructed by ignoring some of the digits had any particular significance."
Dr Jackson says this date and its connection to the Fibonacci sequence might not mean much in itself, but it does remind us of the complexity of nature and the equally complex ways humans have developed to make sense of it.
"There are lots of claims patterns to do with the Fibonacci sequence that are perhaps not actually that true. In fact it's a good opportunity for some home science out there. One is to count the number of petals on flowers and also to look at spirals in the seeds of something like a daisy. So you usually get left-curling spirals and right-curling spirals, in fact they will tend to conform to consecutive Fibonacci numbers as a general rule of thumb and there are reasons for this. It's to do with the way the seeds form. And there are lots of mathematical patterns which will produce a Fibonacci sequence but sometimes people give it more credit than it should be given."
