## From Babylon to Arabs

We are so accustomed with seeing the perfect circle, the zero that we cannot imagine it had to be invented. In fact, the invention of zero was a real revolution.

Imagine how the Romans made calculations. For example, when building a villa, how much did they have to pay for 18 rows of 44 poles of 12 sexterts (Roman coin)? That meant XVIII by XLIV by XII... This calculation took one hour using an abacus. Today, a 10-year old kid does it in less than 2 minutes. But the Romans did not know the number zero.

Zero is the symbol of void. But this figure gives another dimension to the numbers. One zero multiplies by 10, two zeros multiply by 100, and so on. Zero revolutionized the way of counting. The numbers are defined by the position of the forming figures. This is position numbering. Right to left, the first figure represents the units, the second figure the tens, the third the hundreds and so on. Compare CDLXXXVIII with 488.

Calculations - adding, multiplication, division and subtraction - are simpler this way. These numbers allow us "mental calculations".

In **Babylon** (modern Iraq), savants had invented the "zero" during the 4th century BC. But their numbering system was not transmitted to other people because of its peculiarity: the first group (that of the units) was not made of 10, but 60 figures. That corresponded to our system of time counting: one minute has 60 seconds, one hour has 60 minutes.

In Mezoamerica, the **Maya** people invented the "zero" as well, during the 4th-5th centuries AD. But their system remained inside their society. Starting with the 10th century AD, this society entered into a gradual decline, and its mathematical achievements were lost.

One century after the Mayans, around the year 600 AD, Hindu savants invented too the figure "zero". They also invented the position numbering. Arabs learned this figure system from India. They even called them "Indian figures". During the 10th century, these numbers (0,1,2,3,4,5,6,7,8 and 9), slightly changed, were taken over by the Europeans from the Arabs, like many other important items not invented by them (**paper** is one example). That's why we call them "Arabian figures".

The "language" of computers is even more simplified: it operates with just two digits, 1 and 0.