Calculating with fingers
Even before man used written symbols, i.e. signs for numerals and operations, he dabbled with representational images. Fingers were the first and most popular calculating aids. In addition to understanding numbers, this method of calculating required a great deal of skill and dexterity. The development of calculating with fingers cannot be accurately traced back. The practices applied were passed on only by practical use from one generation to the next.
First transcription of counting with fingers
It can be assumed that calculating with fingers had generally been standard practice in administration in the time of the Pharaohs as well as in ancient Greece and Persia. At the beginning of the Common Era and even several centuries later, this system of counting reached its highest level throughout the Roman Empire. It must be assumed that it was widespread and served merchants as a means of understanding across all language barriers. The first scholar who strove towards a transcription was the Venerable Bede (circa 673–735), the English Benedictine monk. In his book "De ratione temporum", he provided a complete explanation of counting with fingers and rules for this method of calculating. With both hands it was possible to represent all the numbers from 1 to 9,999.
Calculating with fingers in "Liber abaci"
Calculating with fingers held its ground for a long time alongside the abacus and calculating with Indo-Arabic numerals since it enabled not only counting or addition and subtraction but also higher calculations. The method of calculating with one's fingers was popular with scholars to the extent that a calculation manual was regarded as complete only if it contained a description of this method.
So it is hardly surprising either that such a primitive means of communication was explained in "Liber abaci". At the end of the first chapter there is a sophisticated system of counting with fingers prized by Fibonacci as an aid for calculating in the place-value system. The skill of calculating with fingers was preserved in various societies over a long period since it was always a reliable and proven calculation aid. In the Central European area it was only pushed into the background by the triumph of written calculation with Indo-Arabic numerals.