By Andy Keedwell

An odd number?

It’s a very odd number — although, in fact, it’s not odd at all, it’s even (it can be divided by two)! Add it or subtract it and no change results; multiply by it and the answer is nothing; but division gives an answer of infinity … Today,it’s usually shown by a circle 0.It is,of course, zero.

An important invention

We’re so used to having a zero that we forget that it was one of the most important mathematical inventions of all time.Ancient Greek mathematicians hated it — how could nothing be something? But without zero, we’re lost.We need it to show place: the difference, for example, between 2, 20 and 200,000.But zero is also a number as real as any other, although it behaves in strange ways.

From Babylon to India and beyond

Three thousand years ago, the Babylonians had something like a zero although it looked more like a hook or a dash.It was the Indian civilisation (and its mathematician Brahmagupta) which really developed the use of zero, in the seventh century AD.From India, it spread to Persia and China and then to Arab traders who called it ‘sifr’:empty.

Fibonacci’s ‘Hindu numbers’

Until medieval times, Europe had been content to be zero-less but it was becoming much harder to calculate using the old Roman numerals.Living in Algeria, a young Italian man called Leonardo Fibonacci came across what were called ‘Hindu numbers’and (along with decimals and ways of calculating interest rates) exported zero to Italian commercial communities.

Where does the name come from?

‘Sifr’ became ‘zero’ in Venetian, from the word for the west wind.And why the 0 shape? One theory says that it comes from the first letter of the Greek word for nothing or perhaps it represents the ‘obol’, a Greek coin of very little value.

Zero today

Today we’d struggle to manage without zero.From the 1950s, the binary system which depends on zero was used to develop computer programming languages.Zero is the freezing point of water, but in the Kelvin scale the lowest temperature that can possibly exist.So each time you give your mobile number, it’s worth remembering: it may be nothing but it’s something!

Activity 1

Before you read, match the word or phrase to a def inition.

a.anumbergreater than any f inite value

b.divisible exactly by two

c.not divisible exactly by two

d.manage to do something w ith diff iculty

e.the extra amountyou pay a bank to borrow money

f.the temperatureatwhich a liquid becomes solid

1.even (number) 2.freezing point 3.inf inity 4.interest rate 5.odd (number) 6.struggle

Activity 2

Now complete the sentences using words and phrases from the text.Make any changes to the words that are necessary.

1.‘Daddy, how many numbers are there?’ ‘The answer is (______) — there are too many numbers to count.’

2.I am going to change to New Bank because their (______) are lower and so I w ill be paying less each month.

3.They (______) to save enough money, but after many months they were able to buy the new car.

4.Two, four, six, eight and ten are all (______) numbers, while one, three, f ive,seven and nine are all (______) numbers.

5.When it reaches (______) in w inter we can go ice skating on the lake.

Activity 3

Put the events from the text in chronological order (from the f irst in time to the last in time).

1.Arab traders called it ‘sifr’.

2.Fibonacci exported zero to Italian commercial communities.

3.In India, Brahmagupta really developed the use of zero.

4.The Babylonians had something like a zero that looked more like a hook or a dash.

5.The binary system was used to develop computer programm ing languages.

6.Zero spread to Persia and China.

7.Fibonacci came across ‘Hindu numbers’.

Activity 4

How would you w rite each of the numbers below in f igures, or say them? Think about how many zeros there are!

1.1

2.10

3.100

4.1,000

5.10,000

6.100,000

7.1,000,000

Activity 5

Do you know any strange or unusual numbers? Why are they strange or unusual?