5-2023 How maths saved a blunder

New Year is just round the corner. Some years ago, I wrote about the most famous mathematics blunder created by man. Now, I explain why the blunder is still surviving and celebrated by everyone. Mathematics is at play once again. In spite of the irrational reason for using 360 as a base for dividing a circle, there are some advantages of this choice. The mathematical justification is explained in two videos: Video #1 and Video #2. The choice of 360 is not so bad, since 360 is a "highly composite number" and is easy to remember. Watch the two videos for more elaborate explanations. Highly composite numbers were a favourite of the Indian genius Ramanujan.


4-2023 What is ISBN ? How does it work ?

Have you ever noticed on the back cover of every book is a barcoded pattern with some numbers ? Ever wondered what could that possibly mean ? According to wikipedia "The International Standard Book Number (ISBN) is a numeric commercial book identifier that is intended to be unique. Publishers purchase or receive ISBNs from an affiliate of the International ISBN Agency. " It helps librarians and bookstores keep track of books in their custody. The bar code replaces the ISBN for automated inventory control.

The ISBN is structured as in the digram given on the right:

Recently, my new book on Ramanujan got an ISBN: 978-1-5457-5712-3 (shown in the image below).
Also see:: How do barcodes work in the book publishing industry ?


3-2023 La langue la plus bizarre que j'ai apprise !

Le français, que j'adore et je maîtrise bien est pleine de pièges et d'enigmes. Voici quelques exemples ::


2-2023 Prophet Muhammad family history

Extracted from : https://en.wikipedia.org/wiki/Wives_of_Muhammad Muhammad, the final Islamic prophet, was born and lived in Mecca for the first 53 years of his life (c. 570–632 CE) Prophet Muhammad‘s family included 13 wives, who are referred to as the ‘Mothers of the Believers‘. Although Muslims are limited to having only four wives at a time, Muhammad was exempted from this ruling and was allowed to have an unlimited number of wives. Little is known about the early life of Aisha. Aisha was prophet Muhammad's third and youngest wife. A preponderance of classical sources converge on Aisha being 6 or 7 years old at the time of her marriage, and 9 at the consummation. At the age of 25, Muhammad married his first wife, the widow Khadija bint Khuwaylid. This marriage lasted for 25 years. Prophet Muhammad‘s family included 13 wives, who are referred to as the ‘Mothers of the Believers‘. No. Consort Married 1 Khadijah 595–619 2 Sawdah 619–632 3 Aishah 623–632 4 Hafsah 625–632 5 Umm al-Masakin 625–626 6 Umm Salamah 625–632 7 Zaynab 627–632 8 Juwayriyyah 628–632 9 Umm Habibah 628–632 10 Safiyyah 629–632 11 Maymunah 629–632 12 Rayhanah 627–631 13 Mariah 628–632 The relevant part of his family tree is here.


1-2023 What is semitism (or anti-semitism) ?

Semitism denotes both a race and a language family.The name Semite comes from Shem, the eldest of the three sons of Noah -- Shem, Ham, and Japheth. In the Greek and Latin versions of the Bible, Shem becomes Sem, since neither Greek nor Latin has any way of representing the initial sound of the Hebrew name. In later times, the idea was widely adopted that the three sons of Noah represented the eponymous ancestors of three major racial or linguistic groups. Ham was the ancestor of the dark-skinned peoples of Africa, Shem of the Hebrews and their various cognates, and Japheth the ancestor of the Medes, Persians, Greeks, and other peoples who, many centuries later, came to be known as Aryans. Over the years, "Anti-semitism" gradually transformed into "anti-Hebrew" or "anti-Jew".


4-2021 Ramanujan Prizes in mathematics, from India and more

Srinivasa Ramanujan, the legendary Indian mathematician, has inspired many mathematicians in India and worldwide. It is no surprise that his name is associated with some major prizes and awards in mathematics.

According to
there are at least two major prizes awarded in mathematics, from India. These are awarded by SASTRA University and ICTP (along with the Gov. of India and IMU).


* ICTP --

The third, called as "Srinivasa Ramanujan Medal", is awarded by Indian National Science Academy:

In addition to the above, Infosys Science Foundation awards prizes in six categories of science, including mathematics :

There are many more awards and prizes for mathematics worldwide


3-2021 Do'nt look before you leap !

Sometimes, it is wiser not to look before you leap. Here is the personal experience I had 41 years ago !

That is why they say "fortune favours the bold".


2-2021 This may happen to you, if you are a mathematician taking a flight !

Why should mathematicians avoid flying ?

This may happen to you too .....

Flight attendant: Is there a doctor on board?
Me: Yes, but I'm not that kind of…
Flight attendant: The pilots are arguing about whether there are as many irrational numbers as rational numbers.
Me: Okay. I’m here.

(Based on a Tweet by @LongFormMath, Jay Cummings, 2021-09-28)


1-2021 The mathematician who was a tramp

Paul Erdos PGOM, LD, AD,LD, CD

Paul Erdos was a brilliant hungarian mathematician. He was known both for his social practice of mathematics (he engaged more than 500 collaborators) and for his eccentric lifestyle. He did not have a roof of his own, and spent his life as a nomadic tramp.

Possessions meant little to Erdős; most of his belongings would fit in a small suitcase, as dictated by his itinerant lifestyle. Awards and other earnings were generally donated to people in need and various worthy causes. He spent most of his life traveling between scientific conferences, universities and the homes of colleagues all over the world. He earned enough in stipends from universities as a guest lecturer, and from various mathematical awards, to fund his travels and basic needs; money left over he used to fund cash prizes for mathematicians.

He would typically show up at a colleague's doorstep and announce "my brain is open", staying long enough to collaborate on a few papers before moving on a few days later. In many cases, he would ask the current collaborator about whom to visit next.

Who is a PGOM LD AD LD CD ? See this video for the answer.

This, and many more similar stuff is available here. Take a look.

Who says, mathematicians have no sense of humour ?



5-2018 Who is better : Norbert Wiener or Albert Einstein ?

Norbert Wiener was in fact a very absent minded genius.

The following story is told about him: When they moved from Cambridge to Newton, his wife, knowing that he would be absolutely useless on the move, packed him off to MIT while she directed the move. Since she was certain that he would forget that they had moved and where they had moved to, she wrote down the new address on a piece of paper, and gave it to him.

Naturally, in the course of the day, an insight occurred to him. He reached in his pocket, found a piece of paper on which he furiously scribbled some notes, thought it over, decided there was a fallacy in his idea, and threw the piece of paper away.

At the end of the day he went home (to the old address in Cambridge, of course). When he got there he realized that they had moved, that he had no idea where they had moved to, and that the piece of paper with the address was long gone.

Fortunately inspiration struck. There was a young girl on the street and he conceived the idea of asking her where he had moved to, saying, "Excuse me, perhaps you know me. I'm Norbert Wiener and we've just moved. Would you know where we've moved to?" To which the young girl replied, "Yes daddy, mommy thought you would forget."

That's not all about Weiner.....

According to one of his biographers, Norbert Weiner spent 30 years “wandering the halls of MIT, like a duck”, one of its most well-regarded and renowned professors of mathematics, especially known for his absent-mindedness:

“His office was a few doors down the hall from mine. He often visited my office to talk to me. When my office was moved after a few years, he came in to introduce himself. He didn’t realize I was the same person he had frequently visited; I was in a new office so he thought I was someone else.”— Phyllis L. Block

“He went to a conference and parked his car in the big lot. When the conference was over, he went to the lot but forgot where he parked his car. He even forgot what his car looked like. So he waited until all the other cars were driven away, then took the car that was left.” — Howard Eves

“When we met, was I walking to the faculty club or away from it? I’m wondering, because in the latter case I’ve already had my lunch”

Weiner or Einstein ? Who is better ? You be the judge.

And now, some good ones about Einstein:

1.Einstein takes a train

2. Gone for lunch

3. And now, find out who is better -- Einstein or Chaplin ?

When Einstein met Chaplin in 1931, Einstein said, “What I admire most about your art is its universality. You do not say a word, and yet the world understands you."

“It's true.” replied Chaplin, "But your fame is even greater. The world admires you, even though they don't understand a word of what you say ."

That's what geniuses are made of.