Puzzles - Missing letters puzzles

Exercise : Missing letters puzzles
163.
Answer
:
N
Explanation
:
Starting at the top left hand of every diagram, move around the outer circles in an anti-clockwise direction. Letters are written in alphabetic sequence, in steps given by the numerical value of the central letter.

164.
Answer
:
E
Explanation
:
Starting on the left, and moving to the right, letters are written in alphabetical order, moving forward 8 places, then back 2, then forward 7 places and back 3. Repeat this sequence to the end of the line.

165.
Answer
:
W
Explanation
:
Start with A on the left hand side, and move in a clockwise spiral around the diagram. Letters advance through the alphabet in steps of 6.