Billy Preston’s 1974 hit illustrates a concept that it took the best mathematical minds over two millennia to grasp.
The Babylonians, as far back as 2000 BCE, first conceived of a mark to indicate the absence of a number in a string of numbers. The Indian mathematician, Brahmagupta, in around 650 AD began to formalise the use of zero in mathematical operations. He distinguished between the use of zero as a sunya – meaning empty or nothing – and kha meaning place, where it represents a null in a string of numbers. He also devised a set of rules for dealing with the addition and subtraction of zero but got division wrong.
The spice traders brought Brahmagupta’s theories to Baghdad. The ninth century mathematician, Al-Khowarizmi, worked on equations which equalled zero and called zero “sifr” from which we have derived our word cipher. He also developed algorithms as a quick method of multiplying and dividing numbers. By 879 AD zero was written as an oval, as it is now.
Zero finally reached Europe in the twelfth century and Italian mathematician, Fibonacci, built on the Arabian mathematician’s work in his book, Liber abaci. The merchant community picked up on his ground-breaking work but the authorities were suspicious of the use of Arabic numerals because they were relatively easy to change. Though it was outlawed, merchants continued to use zero in encrypted messages, known as ciphers.
The work of Descartes – the base point of the Cartesian co-ordinates is 0,0 – and then of Newton and Lebiniz (who independently solved the issues around the division of zero) and the development of calculus really cemented zero’s place in European numerology and the rest is history, as they say.
So is zero odd or even? The standard test for an even number is whether it is divisible by 2. It is. Its place in the list of numbers is between two odd numbers, -1 and 1. So zero is an even number. Remember this if petrol is rationed based on the whether the final number in your registration number is odd or even , as was the case recently in New York.