The 23rd of November is celebrated as ‘Fibonacci day’ because when the date is written in the mm/dd format (11/23), the digits in the date form a Fibonacci sequence: 1,1,2,3.

A Twitter user ranted about how the discovery should be credited to Indian mathematics and not the Bonacci, who helped popularise it in the world.

When written as 11/23, it forms part of the Fibonacci Sequence. The Fibonacci sequence is made of numbers that are written in a sequence that must be the sum of the two previous numbers in the sequence. For example, the date, 11/23 when written in a sequence 1123, represents that the latter number is a product of the first two numbers in the sequence. (1+1=2, 1+2=3!)

While the world credits the European mathematician from the middle ages, Leonardo Bonacci, the concept actually has its roots in Indian mathematics.

Leonardo Bonacci wasn’t the first mathematician to discover this sequence, but he definitely popularised it with his book Liber Abaci. The sequence is also referred to as nature’s numbering system, it is often observed by known people in flower patterns, hurricane patterns, and even galaxies.

In the book Liber Abaci, authored by Bonacci in 1202, the European mathematician has attributed the discovery of the sequence to Indian mathematics.

The Twitter account True Indology @TIinExile busted the myth around the day. In a Twitter thread, he quoted Bonacci from his book Abaci where he confesses that he is simply rewriting the concept he studied from Indian mathematics. “Fibonacci sequence is nature’s code. It is in everything from flowers to storm systems to the shape of galaxies”- they said, crediting Mr. Fibonacci for this “discovery”

According to the translated version of the book, the author lived in Bugia, Algeria, where a colony of Indian Merchants resided and he was introduced to Indian Mathematics. As presented by the Twitter account True Indology, Abaci calls Greek, Arabic Egyptian Math, and Pythagoras to be “**erroneous compared to Indian Mathematics**“.

He further stakes no claim to the concept explained in the book, instead attributes it to Indian mathematics, he writes in the book, ” **In my book, I have published the doctrine of Mathematics completely according to the Method of Indians. I have COMPLETELY adopted the (Mathematical) Method of Indians because it is the MOST effective**“.

Therefore, we can say that when the whole world is celebrating Fibonacci Day on 23^{rd} November, they are actually celebrating Indian mathematicians.

Fibonacci sequences appear in biological settings, such as branching in trees, arrangement of leaves on any stem, the fruits of a pineapple, the flowering of artichoke, an uncurling fern, and the arrangement of a pine cone, and the family tree of honeybees.

Kepler pointed out the presence of the Fibonacci sequence in nature, using it to explain the (golden ratio-related) pentagonal form of some flowers. Field daisies most often have petals in counts of Fibonacci numbers. In 1754, Charles Bonnet discovered that the spiral phyllotaxis of plants was frequently expressed in the Fibonacci number series.

Lionardo made the Fibonacci series famous in the year 1202. But before that, there was Acharya Pingal, Acharya Gopal in 1135 who made it famous. Even Hem Chandra talked about this series in 1150. These were Indian scientists.

Acharya Pingal wrote a book called “Chand Sutra”. In this book, there is information about Pascal’s Triangle and Binomial Theorem. The formula of Fibbonaci is F(n) = F(n-1) + F(n-2).