Answer: 16 Explanation: Starting bottom left and moving clockwise around the triangle, numbers follow the sequence of Square Numbers.

2

Answer: 39 Explanation: Working from top to bottom, double each number and subtract 1, then 2, then 3 etc.

3

Answer: 4 Explanation: Working in columns, the sum of the numbers in each column is always 14.

4

Answer: 6 Explanation: The numbers in each row and column add up to 15.

5

Answer: 40 Explanation: Moving from left to right, numbers increase by 2,3,4 and 5.

6

Answer: 9 Explanation: In each square of the diagram, the sum of the numbers is always 22.

7

Answer: 16 Explanation: Moving clockwise, around alternate segments in the chain, one sequence decreases by 1, 2, 3 and 4 each time, while the other increases by 2, 3, 4 and 5.

8

Answer: 7 Explanation: Starting with the numbers in the top row, and following straight lines through the centre of the diagram, subtract the middle number from the top number to give the corresponding value on the bottom row.

9

Answer: 13 Explanation: In each circle, starting at the top left segment, numbers increase, as you move clockwise, by 2 for the upper left circle, 3 for the upper right, 4 for the lower right and 5 for the lower left.

10

Answer: 3 Explanation: In each group of 3 numbers, the lower number equals the average of the top two numbers.

11

Answer: 1 Explanation: Reading each row as a 3 digit number, the rows follow the sequence of square numbers, from 17 to 19.

12

Answer: 8,1 Explanation: Reading each row as 3 separate 2-digit numbers, the central number equals the average of the left and right hand numbers.

13

Answer: A:58 B:86 Explanation: In the first oval, all numbers are multiples of 8, and in the second, they are all multiples of 7.

14

Answer: 1 Explanation: Reading each pair of numbers as a 2 digit number, they follow the sequence of square numbers from 6 to 9.

15

Answer: 7 Explanation: Taking the top row of circles, numbers in the central circle equal the sum of the numbers in corresponding segments of the left and right hand circles. In the bottom row, numbers in the central circle equal the difference between numbers in corresponding segments of the left and right hand circles.

16

Answer: 253 Explanation: Starting at the top left, and moving through the diagram in a Z shape, double each number and add 3 to give the next number along.

17

Answer: 51 Explanation: Moving to the right, double each number and subtract 3 to give the next number along.

18

Answer: 2 Explanation: Starting with the 10 at the top, one set of numbers increases by 3 each time, written in alternate boxes as you move down the diagram, and the other set of numbers decreases by 2, written in the boxes remaining.

19

Answer: 6 Explanation: On each row, add the values of the left hand and central boxes to give the value in the right hand box.

20

Answer: 10 Explanation: In each star diagram, the number in the centre equals the sum of the top three numbers, subtracting the sum of the bottom two numbers.