# Talk:2046: Trum-

This is not that weird. If names were random then it would be a 1 in 26^4 = 456976 chance of a particular president matching another for the first 4, but this is a "Birthday Problem" with 44 presidents, so the probability of any two presidents sharing the first 4 characters is 1-(456976!/(456976^44 (456976 - 44)!)), which wolfram alpha is giving as 0.206%

Yes, but we already "fulfilled our obligation" after the sixth president :) Zachweix (talk) 15:59, 14 September 2018 (UTC)

An approximation to the correct probability would be to do 44^2/(2 x 26^4) which would give about 0.2% chance of this happening. So fairly weird, but as the comic suggests, many things about this presidency are weirder than 0.2%.

I love that we are now having a mathematical discussion about how weird things are in the presidency. Zachweix (talk) 15:58, 14 September 2018 (UTC)

Should we mention Andrew Johnson and LBJ, perhaps in a "Trivia" section? Obviously Johnson is a very common surname, but they're still unrelated presidents that share the first (and only) 7 characters of their last name. (Are there other pairs of presidents that share at least the 3 first letters of their surnames besides AJ/LBJ and HST/DJT?) 172.69.62.160 16:25, 14 September 2018 (UTC) ...And, upon reflection, I just realized Harding shares the first 3 letters with the Presidents Harrison, so that's one(?) more example.

So we discount Presidents Adams, Bush, Cleveland, Harrison and Rosevelt as being related, or being the same person. We have the following common starts: Bu (3 names), Cl, Ha (3 names), Ta, Har, Trum and Johnson. Also A, B, C, F, G, H, J, M, P, R, T and W. 162.158.154.241 16:49, 14 September 2018 (UTC)

If you count Buren as opposed to Van Buren then you have 4 starting Bu and 2 starting Bur 162.158.155.146 16:52, 14 September 2018 (UTC)