**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.