The Moscow Puzzles

2/11/21's puzzle

88. Cat and Mice
Cat is taking a nap. He dreams he is encircled by 13 mice: 12 black and 1 white. He hears his owner say: "Cat you are to eat each thirteenth mouse, keeping the same direction. The last mouse you eat must be the white one.
   Which mouse should he start from?
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
  ☟ ANSWER ☟
  
  
  88. Cat and Mice
  start from the cross in the diagram (position 13) and go clockwise through positions 1,2,3,..., crossing out each thirteenth dot,
  13,1,3,6,10,5,2,4,9,11,12,7, and 8. Call position 8 the white mouse and Cat starts clockwise from the fifth mouse clockwise from the white mouse 
  (ie postion 13 relative to position 8).  Or he starts counterclockwise from the fifth mouse counterclockwise to the white mouse.
    
    
    (sorry about my diagram if you're some freak with ocd)