Fibonacci

I composed this book from what I had learned from the Indians and through long study and practice.

The first part of the book teaches the method of the Indians and calculations with whole numbers.

The second part treats fractions and their operations.

The third part contains the rule of three and other commercial rules.

The fourth part deals with the extraction of roots.

The fifth part is on geometry and measurement.

If you wish to find the square of any number, multiply the number by itself.

The circle is a round plane figure contained by one line, which is called the circumference.

All right angles are equal to one another.

I have added some things of my own and have left out others as seemed superfluous.

This book is dedicated to Michael Scot, the most learned philosopher and astrologer to the Emperor.

I was born in Pisa, the city of the famous leaning tower.

My father was a customs official in Bugia, Algeria, which is where my mathematical journey began.

The Arabic method of calculation is superior to the Roman method with abacus and counters.

Without the zero, the system of the nine figures would be incomplete.

The zero is called 'zephirum' in Arabic, from which we derive our word 'cipher'.

In business, the most common and useful rule is the rule of three.

If the first term is to the second as the third is to the fourth, then the product of the first and fourth equals the product of the second and third.

A number is a multitude composed of units.

A unit is that by virtue of which each of the things that exist is called one.