Fibonacci: Rabbits, Romans & Software Development

This is a name that gets thrown around a lot. Tons of pop culture references and hardly any of them accurate. He's gotten an honorable mention in everything from The DaVinci Code to Criminal Minds (big fan of both!) and his number sequence plays a critical role in effort assessment in scrum methodology. Although, in that last one, it's not unusual for exhausted, over-extended engineers to throw out seeming random numbers like that's going to magically fix everything. It doesn't.

Why We Should Know This Man

Take a pen and paper and write down the following: Your phone number, your zip code and your birth date. What did that take? 10 second and a couple of square inches of paper? Thank Fibonacci for that one, here's why.

This little math wiz is born around 1170, his Dad is a merchant and works at a trading post. His Dad is known as 'Bonacci' - it means 'the simpleton' so junior takes the name Fibonacci, or 'son of the simpleton'. Well, this simpleton's son is around numbers alot and comes across a new fangled way of keeping track of them. He starts to look at Hindu–Arabic numerals (0-9), he did not invent this but he tries to figure out a way to replace the then standard roman numerals with this new shorthand. In 1202 he publishes his 'Book Of Calculations' where he shows how the shorter Hindu-Arabic (now decimal) numbers can be used to do everyday calculations more easily than Roman numerals.

The world caught on and adopted his technique. Because of this 'son of a simpleton' math became more accessible to the average citizen, leading to a flurry of mathematical discoveries. The world moves on and today we can quickly jot down phone numbers, do long division without our heads exploding and can enter a PIN at an ATM without dissolving into a frustrated mess. That's X.V.I.I.I, no wait, how many I's was that? Damn it!

Why We Do Know This Man

In that same book Fibonacci is trying to show that using what we now consider traditional decimal notation is easier than Roman numerals. To do this he gives some examples of basic math functions done both ways. One of his examples uses a sequence of numbers discovered long before in India, maybe as early as the 6th century. The sequence takes one number and adds it to the number directly before it. The Indians used this series to describe cumulative growth in natural systems. It falls somewhere between a linear pattern and an exponential one, a kind of happy medium that they observed in everything from plant growth to population explosions. Fibonacci takes this and uses it to solve a problem involving the reproductive rate of rabbits. He uses the series to show that if he starts with I rabbits and adds II rabbits he will expect to end up with III rabbits. Then, given some time, he'll have V rabbits, then VIII rabbits etc. He documents this same patten using his fancy new symbols and there your have a Fibonacci sequence. 1,2,3,5,8.....

He did not discover the series but he did introduce the general public to it. For this he gets all the credit. Today, the Fibonacci series has been modified ever so slightly. It is now started with 1, 1 so it becomes 1,1,2,3,5,8.... It has been found all over the natural world, in everything from tree and flower structures to our own DNA. It is closely linked with the golden ratio and turns up everywhere from modern photography to fine art and architecture. This series appears to describe a patten so closely linked to our very existence that we instinctively and subconsciously respond to it, and by 'we' I mean every living thing on earth. This is pretty cool. And even though he did not discover this series, he did bring it to our attention and used Hindu-Arabic notation to present it in a clear and simple form allowing us, for the first time, to glimpse at the possibilities it held.