Puzzle 1: Which letter replaces the question mark?Answer: F
Explanation: Working in rows, from top to bottom, the sum of the numerical values of the letters in each row starts at 12, and increases by 2 as you go down each row.
Puzzle 2: Which letter replaces the question mark?Answer: G
Explanation: The numerical values of the letters in opposite segments of the circle add up to 16 each time.
Puzzle 3: Which letter replaces the question mark?Answer: H
Explanation: Working from top to bottom, letters are written in pairs. Take the 2 digit numerical value of the first letter and add the 2 digits together. Write the letter with this numerical value in the next space down. Continue in this way down the line.
Puzzle 4: Which letter replaces the question mark?Answer: N
Explanation: Moving from left to right, top to bottom letters follow alphabetical order, skipping any letters written with curved lines.
Puzzle 5: Which letter replaces the question mark?Answer: S
Explanation: Working from top to bottom, the numerical values of the letters follow the sequence of Prime Numbers, adding 1, then 2, then 3 etc.