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 ::

Vive la langue !

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".