Puzzle 1: Which number replaces the question mark?Answer:1
Explanation: Reading each row as a 3 digit number, the rows follow the sequence of square numbers, from 17 to 19.
Puzzle 2: Which number replaces the question mark?Answer: 6
Explanation: The number at the centre of each segment equals the sum of the numbers on the outside of the opposite segment.
Puzzle 3: Which number replaces the question mark?Answer: 3
Explanation: Working in rows, the number in the central oval equals the sum of the left and right hand numbers, divided by 3.
Puzzle 4: Which number replaces the question mark?Answer: 16
Explanation: Starting with the top left number, and working down one row at a time, alternating between left and right, double the number each time. Repeat this sequence, starting with the top right number.
Puzzle 5: Which number replaces the question mark?Answer:13
Explanation: As you move from left to right, the sum of the digits in each circle forms a sequence of multiples of 6, from 6 to 30.