+---+---+  +---+---+  +---+---+  +---+---+  +---+---+ 
  | C | D |  | I | H |  | E | G |  | F | B |  | E | I |  
  +---+---+  +---+---+  +---+---+  +---+---+  +---+---+ 
  | B | H |  | A | G |  | J | C |  | D | F |  | A | J |
  +---+---+  +---+---+  +---+---+  +---+---+  +---+---+  
  +---+---+  +---+---+  +---+---+  +---+---+  +---+---+ 
  | A | E |  | B | G |  | H | J |  | H | E |  | C | B |  
  +---+---+  +---+---+  +---+---+  +---+---+  +---+---+ 
  | I | G |  | C | F |  | F | I |  | A | D |  | D | J |
  +---+---+  +---+---+  +---+---+  +---+---+  +---+---+ 
  +---+---+  +---+---+  +---+---+  +---+---+  +---+---+ 
  | G | I |  | F | D |  | B | E |  | H | J |  | H | F |  
  +---+---+  +---+---+  +---+---+  +---+---+  +---+---+ 
  | A | D |  | B | E |  | C | G |  | J | I |  | A | C |
  +---+---+  +---+---+  +---+---+  +---+---+  +---+---+ 
  +---+---+  +---+---+  +---+---+  +---+---+  +---+---+ 
  | E | F |  | I | J |  | B | A |  | C | G |  | D | E |  
  +---+---+  +---+---+  +---+---+  +---+---+  +---+---+ 
  | F | H |  | J | H |  | A | D |  | G | C |  | I | B |
  +---+---+  +---+---+  +---+---+  +---+---+  +---+---+ 
  +---+---+  +---+---+  +---+---+  +---+---+  +---+---+ 
  | J | B |  | C | D |  | F | D |  | B | A |  | H | G |  
  +---+---+  +---+---+  +---+---+  +---+---+  +---+---+ 
  | C | J |  | E | A |  | H | I |  | I | E |  | G | F |
  +---+---+  +---+---+  +---+---+  +---+---+  +---+---+

Each of the 25 blocks of four letters shown above can be rotated about its center, either 90^o clockwise, 90^o anti-clockwise or 180^o. When all the blocks are in their correct orientations, all the ten rows and columns contain the letters A to J exactly once.

Sixteen of the blocks shown above are not in their correct orientations. Which 16 out of the 25 blocks have been rotated and in which direction(s)?

(In reply to bang by Hedda Dunn)

HOW  DOES YOUR COMMENT RELATE TO THE GIVEN PROBLEM!

Edited on April 19, 2024, 10:18 pm

Posted by K Sengupta on 2024-04-19 22:10:59