# Who Was Leonardo Pisano Fibonacci and What Did He Contributed to Maths?

Leonardo Pisano Fibonacci (1170–1240 or 1250) was an Italian mathematician and a number theorist. He introduced the world to such wide-ranging mathematical concepts as what is now known as the Arabic numbering system, the concept of square roots, number sequencing, and even math word problems. Leonardo Fibonacci traveled the world in the early thirteenth century. During his travels, Fibonacci learned about how other countries practiced math. He was very interested in how people did math in India and the Middle East.

When he came back to Italy, Fibonacci wrote a book titled Liber Abaci, (Book of the Abacus), the first European work on Indian and Arabian mathematics. This book was about all the math Fibonacci learned on his travels! Liber Abaci is where modern mathematicians found the Fibonacci Sequence. However, Indian mathematicians knew about the pattern centuries before Fibonacci wrote about it in his book!

What’s the trick to the Fibonacci Sequence? To find the next number in the sequence, just add the two previous numbers! Here’s what that looks like:

0 + 1 = 1, 1 + 1 = 2, 1 + 2 = 3, 2 + 3 = 5… and so on! The Fibonacci Sequence never ends!

It may be ancient, but this special pattern is still useful, we use the Fibonacci Sequence to make predictions. People who work in trade use it to predict changes in the stock market. This helps us know what to expect to happen in the economy! In nature, we can use the Fibonacci Sequence to predict how many honey bees live in a hive. Botanists even use it to predict how many petals will grow on a flower!

The next time you’re at the beach, look closely at a seashell! The spiral shapes of some seashells follow the Fibonacci Sequence. Mathematicians call the pattern the Golden Spiral, and they replicate it by drawing a series of connected squares whose areas match the numbers from the Fibonacci Sequence. Seashells are only one place the Golden Spiral shows up in nature. You can also see it in the pattern of seeds on a sunflower, the arrangement of seed pods on a pine cone, and even the shape of galaxies.