I don’t agree in step number 7 because at that moment you don’t know if the diagonal (A5-E1) or the column (C1-C5) are the ones that contain letters.

If the letters were in the column, that would mean there would be no numbers in that column, which could not fulfill the clue in D4.

The clue in B2 says that no letter or number is in the name of its cell. For all 5 letters to be in column C, this rule will be violated as C will be in a cell which has ‘C’ in its name.

D4 clue requires each row and column to have exactly one number — that should be clarified in the solution, as it leads to the diagonal being the only option for the five letters.

All of you are right, it was my mistake. Thanks all you guys.

I don’t agree in step number 7 because at that moment you don’t know if the diagonal (A5-E1) or the column (C1-C5) are the ones that contain letters.

If the letters were in the column, that would mean there would be no numbers in that column, which could not fulfill the clue in D4.

The clue in B2 says that no letter or number is in the name of its cell. For all 5 letters to be in column C, this rule will be violated as C will be in a cell which has ‘C’ in its name.

D4 clue requires each row and column to have exactly one number — that should be clarified in the solution, as it leads to the diagonal being the only option for the five letters.

All of you are right, it was my mistake. Thanks all you guys.