Leonardo Pisano, known as Fibonacci, was an Italian mathematician, considered to be the most talented mathematician of the Middle Ages. One of Leonardo's mathematical formulas that he is most famous for is the Fibonacci Sequence.
The Fibonacci Sequence is calculated by the fact that every number after the first two is the sum of the two preceding numbers:
1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144
For example - 144=89+55 OR 34=21+13
This formula isn't just used in math, either! It is seen in many things around you - from the arrangement of leaves on a tree, to the way sunflower seeds are laid out on the flower!