The book is now available! 7
(another Prime Pages' Curiosity)
Prime Curios!
Curios: Curios Search:

Single Curio View:   (Seek other curios for this number)


The smallest example of x-y,xx-y,xxx-y all being prime is with digits x=7 and y=4. So 7-4=3, 77-4=73, 777-4=773 are all primes. It is the only solution because one of three consecutive numbers x..x-y is divisible by 3. [Luhn]


  Submitted: 2002-03-15 15:22:37;   Last Modified: 2008-01-30 11:28:00.

Prime Curios! © 2000-2018 (all rights reserved)