A character in a novel I was reading used the passcode 1729 for his house’s security system. He did so because of the famous Hardy-Ramanujan anecdote about the number. That got me to thinking. What would mathematicians of the past have used for their passcodes? I tweeted some ideas and got some great responses with additional suggestions.

Here’s my list with some other additions. I’ve linked to biographies of the individuals and linked to the reasons why I chose the number that I did.

- Archimedes: 3141
- Srinivasa Ramanujan: 1729
- Fibonacci: 1123
- Euclid: 2357
- Brahmagupta: 0000
- Giuseppe Peano: 0123
- Hippasus of Matapontum: 1414
- Leonhard Euler: 2718
- Gottfried Leibniz: 7853
- Isaac Newton: 6674
- Carl Gauss: 5050
- Luca Pacioli: 1618
- Eugène Charles Catalan: 1125
- Édouard Lucas: 2134
- Marin Mersenne: 3731
- Pierre de Fermat: 3517
- Alexander Grothendieck: 0057
- Blaise Pascal: 1331
- Mitchell Feigenbaum: 4669
- Zeno of Alea: 1248
- John Napier: 6931
- David Singmaster: 3003
- D. R. Kaprekar: 6174
- Michael Mästlin: 6180
- Lorenzo Mascheroni: 5772
- Alexander Gelfond: 2314
- D. G. Champernowne: 1234
- Wacław Sierpiński: 1585
- John H. Conway: 1303
- François Viète: 6366