Forex Fibonacci Levels is a Freeware offline Fibonacci levels calculator. Leonardo Fibonacci (1170 - 1250) was a Middle Ages mathematician born in the Italian city of Pisa. He is most known with his "Book of Calculation" and the number sequence named Fibonacci Numbers. In the Fibonacci sequence of numbers, each number after the first two is the sum of the previous two numbers. Thus the sequence is 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, etc.