Please turn on javascript in your browser to play chess.
Posers and Puzzles

Posers and Puzzles

  1. Standard member Mathurine
    sorozatgyilkos
    18 Apr '07 15:15
    2007 is divisible by 9. If a 1 be added onto the end... 20071, the number is prime. What can be added to the end of 20071, to obtain another prime?

    What delights can be found beyond?
  2. Standard member DeepThought
    Losing the Thread
    18 Apr '07 15:52 / 1 edit
    Brute force numerical calculation tells me to keep adding 3s. Is there a trick to see it without a computer?
  3. Standard member Mathurine
    sorozatgyilkos
    18 Apr '07 16:04 / 1 edit
    Originally posted by DeepThought
    Brute force numerical calculation tells me to keep adding 3s. Is there a trick to see it without a computer?
    probably...
  4. Standard member emanon
    Student
    21 Apr '07 16:04
    Originally posted by Mathurine
    probably...
    well?...