Actually, that should read ‘Stamps on Numbers’. But ‘Stamp on Numbers’ is something I would have liked to say to my Math teachers, so let me work it out my system!

Browsing through the books in the home bookshelf is an obsessive COVID activity with me, as with many others. In this exercise, I came across a book entitled ‘Wonder of Numbers’ by Clifford Pickover. While I am sure the book has lots to teach on mathematics, what I found most interesting was a snippet that the country of Nicaragua had, in 1971, issued a series of stamps called the “The 10 mathematical formulas which have changed the face of the world”. The ten selected formulae:

- 1 + 1 = 2
- Pythagorean law for right-angled triangles
- Archimedes’ law of moments
- Napier’s law of logarithms
- Newton’s law of gravitation
- Maxwell’s law of electromagnetism
- de Broglie’s law of light waves
- Tsiolkovskii’s law of rocket motion
- Boltzmann’s law of entropy, and
- Einstein’s law of relativity.

The back of each stamp apparently has a small explanation of the formula. No one is quite sure how these particular formulae were selected, but what I found most fascinating was that a country would think of putting out such a series!

Delving a little more taught me that there were several hundreds of stamps across the world, devoted to mathematics and mathematicians.

Nicaragua, Iran and Mexico have brought out stamps on the theme of ‘Counting on Fingers’. There are several stamps which highlight calculating instruments like Pascal’s Mechanical Calculator, William Schickard’ calculating device,* *the Slide Rule, etc.

A number of stamps have featured statistical themes, such as a graph showing the Norwegian gross national product growth from 1876 to 1976, and one depicting the decline in malaria.

There have been many stamps devoted to games and pastimes based on mathematical reasoning. Chess and Go—a Chinese game—have quite a few each. But so do other lesser known ones–*Senet* an early form of backgammon; an Egyptian game from 1350 BC played by two players on a 3 x 10 board; the African game of *eklan* which consists of a board with 24 holes, arranged in concentric squares into which sticks are inserted etc. Of course, the *Rubik cube*, invented by the Hungarian engineer Erno Rubik, a coloured cube whose six faces can be independently rotated so as to yield 43,252,003,274,489,856,000 different patterns, has a stamp or two.

The metric system was introduced in 1960 and gradually, most countries have adopted this system of weights and measures. There are quite a few ‘metrication stamps’ including:

- a Brazilian metric ruler
- a Romanian stamp demonstrating that a metre is one ten-millionth of the distance from the north pole to the equator
- a stamp from Pakistan demonstrating the metric units of weight, capacity and length
- two Australian cartoon stamps featuring the metric conversion of length and temperature
- a Ghanaian stamp indicating that a metre of cloth is a little more than 3 feet 3 inches.

Since 1897, International Congresses of Mathematicians have been held at which thousands of mathematicians from around the world gather to learn about the latest developments in their subject. These meetings usually take place every four years. Several of these congresses have been commemorated by stamps.

India has a few mathematical stamps too. Aryabhatta, Ramanujam and DD Kosambi are celebrated on Indian stamps. Jantar Mantar, the remarkable observatory designed by mathematicians and astronomers figures on a stamp too. The decimal system which originated in India and is a fundamental contribution, is actually celebrated in a stamp brought out by Nepal through a depiction of an Ashoka Pillar from Lumbini, which portrays this.

My search engine wanderings led me to a world which I did not know existed, and from where I have gleaned most of this information. The world of people who love mathematics, stamps and mathematical stamps .

Some of these, which are also the sources of much of the above information:

https://mathematicalstamps.eu/news/100

http://users.wfu.edu/kuz/Stamps/stamppage.htm

*Stamping through Mathematics. *Robin J. Wilson. Springer.

*Mathematics and science : an adventure in postage stamps.* William L.Schaaf. Reston.

Have fun!

–Meena