21. 2
3
4
5

```Answer

Answer: Option  A 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. ```

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22. 2
4
6
8

```Answer

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

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23. 4
6
8
10

```Answer

Answer: Option  D 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. ```

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24. 21
23
25
27

```Answer

Answer: Option  B Explanation:Starting top left, and moving down in columns from left to right, the numbers follow the sequence of
prime numbers from 2 to 23. ```

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25. 10
12
14
16

```Answer

Answer: Option  A Explanation:Numbers in the segments of the left hand circle equal the difference between numbers in corresponding
segments of the two right hand circles. ```

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