# Number Logic Practice 1

In this practice exercise, students will identify a rule which is used to make a number and apply this rule to find a missing number.

Key stage:  KS 2

Curriculum topic:   Exam-Style Questions: Verbal Reasoning

Curriculum subtopic:   Exam-Style Questions: Number Logic

Difficulty level:

### QUESTION 1 of 10

The following activity is a practice exercise to help you measure your success under timed conditions.

If you are unsure of an answer, move on to the next question.

You should come back to questions you found difficult at the end if you have time.

Let's try one together as a reminder:

We need to work out how the numbers on the outside of the brackets create the numbers on the inside of the brackets and then apply the same rule to the third set of brackets.

10 (23) 3        5 (16) 6        2 ( _ ) 5

First, we need to find a way to make 23 using 10 and 3.

If we add 10 and 3 together we get 13.

Then, if we add another lot of 10, we get to 23.

So the rule could be: add the two outside numbers and then add the first number again.

Apply to the second set of numbers: 5 + 5 + 6 = 16.

We’ve found the rule.

Then we use the rule to work out the missing number in the final set: 2 + 2 + 5 = 9.

The missing number is 9.

Now it's time to begin this practice exercise.

Good luck!

Look at the numbers below.

6 (45) 7        3 (39) 12        8 (?) 11

What is the mystery number?

80

88

90

91

93

Look at the numbers below.

3 (28) 5        9 (109) 10        6 (?) 7

What is the mystery number?

51

52

53

54

55

Look at the numbers below.

10 (23) 3        6 (21) 9        2 (?) 5

What is the mystery number?

8

9

10

11

12

Look at the brackets below.

6 (46) 20        3 (19) 8        7 (?) 10

What is the mystery number?

25

26

27

28

29

Look at the numbers below.

10 (21) 5        4 (17) 7        16 (?) 4

What is the mystery number?

23

22

25

21

26

Look at the numbers below.

5 (53) 10        6 (21) 3        7 (?) 4

What is the mystery number?

28

29

30

31

32

Look at the numbers below.

7 (32) 5        10 (14) 2        6 (?) 8

What is the mystery number?

71

70

72

75

69

Look at the numbers below.

5 (8) 60        7 (4) 56        10 (?) 100

What is the mystery number?

6

5

7

4

9

Look at the numbers below.

66 (23) 10        24 (4) 8        90 (?) 7

What is the mystery number?

37

38

39

40

41

Look at the numbers below.

3 (49) 4        7 (121) 4        6 (?) 3

What is the mystery number?

80

81

100

82

76

• Question 1

Look at the numbers below.

6 (45) 7        3 (39) 12        8 (?) 11

What is the mystery number?

91
EDDIE SAYS
The first set of numbers: 6 (45) 7 The number in the middle is bigger than the outside numbers, a clue that we are multiplying. 6 x 7 = 42 42 + 3 = 45. The rule is 'left number x right number + 3'. Apply to second set: 3 (39) 12 3 x 12 = 36 36 + 3 = 39 Work out the mystery number: 8 (?) 11 8 x 11 = 88 88 + 3 = 91
• Question 2

Look at the numbers below.

3 (28) 5        9 (109) 10        6 (?) 7

What is the mystery number?

55
EDDIE SAYS
The first set: 3 (28) 5 5² = 25 and if we add the 3, we get 28. The rule could be 'right number squared + left number'. Apply to second set: 9 (109) 10 10² (left number) + 9 = 109 (middle number) The rule works. Work out mystery number: 6 (?) 7 7² (49) + 6 = 55
• Question 3

Look at the numbers below.

10 (23) 3        6 (21) 9        2 (?) 5

What is the mystery number?

9
EDDIE SAYS
The numbers in the middle of the brackets are bigger than the outside numbers, we a clue that we are adding. The first set: 10 (23) 3 10 + 3 = 13 and if we add another 10 (which is the number on the left) to 13 we get 23. The rule could be 'left number + right number + left number'. 6 (21) 9 6 + 9 = 15 and if we add another six (left number) we get 15. Work out the mystery number: 2 (?) 5 2 (left number) + 5 (right number) + 2 (left number) = 9
• Question 4

Look at the brackets below.

6 (46) 20        3 (19) 8        7 (?) 10

What is the mystery number?

27
EDDIE SAYS
The rule was 'left number + right number + right number'. Apply to the first number set: 6 (46) 20 6 + 20 + 20 = 46 Apply to second number set: 3 (19) 8 3 + 8 + 8 = 19 Work out the mystery number: 7 (?) 10 7 + 10 + 10 = 27
• Question 5

Look at the numbers below.

10 (21) 5        4 (17) 7        16 (?) 4

What is the mystery number?

26
EDDIE SAYS
The rule was 'left number + right number + 6'. Apply to the first set of numbers: 10 (21) 5 10 + 5 + 6 = 21 Apply to the second set: 4 (17) 7 4 + 7 + 6 = 17 Work out the mystery number: 16 (?) 4 16 + 4 + 6 = 26
• Question 6

Look at the numbers below.

5 (53) 10        6 (21) 3        7 (?) 4

What is the mystery number?

31
EDDIE SAYS
The rule is 'left number × right number + 3'. Apply to second set: 6 x 3 = 18 18 + 3 = 21 Work out mystery number: 7 (?) 4 7 x 4 = 28 + 3 = 31
• Question 7

Look at the numbers below.

7 (32) 5        10 (14) 2        6 (?) 8

What is the mystery number?

70
EDDIE SAYS
The rule is 'right number squared + left number'. Apply to first set: 7 (32) 5 5² = 25 25 + 7 = 32 Apply to second set: 10 (14) 2 2² = 4 4 + 10 = 14 Work out mystery number: 6 (?) 8 8² = 64 64 + 6 = 70
• Question 8

Look at the numbers below.

5 (8) 60        7 (4) 56        10 (?) 100

What is the mystery number?

6
EDDIE SAYS
The rule is 'right number ÷ left number - 4'. Apply to the first set: 5 (8) 60 60 ÷ 5 = 12 12 - 4 is 8 Apply to second set: 7 (4) 56 56 (right number) ÷ 7 (left number) = 8 8 - 4 = 4 Work out the mystery number: 10 (?) 100 100 ÷ 10 = 10 10 - 4 = 6
• Question 9

Look at the numbers below.

66 (23) 10        24 (4) 8        90 (?) 7

What is the mystery number?

38
EDDIE SAYS
The rule is 'half the left number then subtract the right number'. Apply to the second set: 24 (4) 8 Half of 24 = 12 12 - 8 = 4 Work out mystery number: 90 (?) 7 Half of 90 = 45 45 - 7 = 38
• Question 10

Look at the numbers below.

3 (49) 4        7 (121) 4        6 (?) 3

What is the mystery number?

81
EDDIE SAYS
The rule is '(left number + right number)²'. Apply to the first set: 3 (49) 4 3 + 4 = 7 7² = 49 Apply to the second set: 7 (121) 4 7 + 4 = 11 11² = 121 Let's work out the mystery number in the final set: 6 (?) 3 6 + 3 = 9 9² = 81
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