Number Series Test 5

Each of these questions shows a series of numbers. Work out the rule or rules used to arrange the numbers. Then select the answer choice that shows the next number in the series.

21    34    47    60    73     →   

• 86

• 89

• 100

• 96

• 88

Answer explanation

Explanation:    Each term in the sequence is 13 larger than the previous term. Therefore, the next term in the sequence is 73 + 13 = 86.

Question Type A: Adding a Constant 

45    37.5    30    22.5    15     → 

• 9.5

• 7.5

• 8.5

• 13.5

• 12.5

Answer explanation

Explanation:    Each term in the sequence is 7.5 smaller than the previous term. Therefore, the next term in the sequence is 15 - 7.5 = 7.5.           

Question Type B: Subtracting a Constant

21    33    22    41    23    49     → 

• 24

• 27

• 34

• 25

• 23

Answer explanation

Explanation:    There are two sequences. The first sequence is formed of terms 1, 3, 5 and 7. The second sequence is formed of terms 2, 4 and 6. The first sequence adds 1 to get to the next term. The second sequence adds 8 to get to the next term. Therefore, the next term is 23 + 1 = 24.  

Question Type F: Two Sequences - Recurring Pattern

16    39    41    64    66    89     → 

• 93

• 91

• 95

• 101

• 92

Answer explanation

Explanation:    There is one sequence and the difference between adjacent terms is +23 +2 +23 +2 +23. Therefore, the next term in the sequence is 89 + 2 = 91.

Question Type E: One Sequence - Recurring Pattern

105    84    63    42    21     → 

• 2

• 4

• 3

• 0

• 1

Answer explanation

Explanation:    Each term in the sequence is 21 smaller than the previous term. Therefore, the next term in the sequence is 21 - 21 = 0.   

Question Type B: Subtracting a Constant

24    32    51    59    78    86    105     →

• 114

• 113

• 108

• 121

• 118

Answer explanation

Explanation:    There is one sequence and the difference between adjacent terms is +8 +19 +8 +19 +8 +19. Therefore, the next term in the sequence is 105 + 8 = 113.

Question Type E: One Sequence - Recurring Pattern

11    4    24    18    6    31    25    8     →

• 40

• 41

• 39

• 48

• 38

Answer explanation

Explanation:    There are three sequences. The first sequence is formed of terms 1, 4 and 7. The second sequence is formed of terms 2, 5 and 8. The third sequence is formed of terms 3, 6 and 9. The first sequence adds 7 to get to the next term. The second sequence adds 2 to get to the next term. The third sequence adds 7 to get to the next term. Therefore, the next term is 31 + 7 = 38.

Question Type G: Three Sequences - Recurring Pattern

20    23    18    28    31    26    36     → 

• 39

• 42

• 41

• 40

• 49

Answer explanation

Explanation:    There is one sequence and the difference between adjacent terms is +3 -5 +10 +3 -5 +10. Therefore, the next term in the sequence is 36 + 3 = 39.

Question Type E: One Sequence - Recurring Pattern

16    5    27    7    38    9     →

• 50

• 51

• 53

• 49

• 52

Answer explanation

Explanation:    There are two sequences. The first sequence is formed of terms 1, 3, 5 and 7. The second sequence is formed of terms 2, 4 and 6. The first sequence adds 11 to get to the next term. The second sequence adds 2 to get to the next term. Therefore, the next term is 38 + 11 = 49.

Question Type F: Two Sequences - Recurring Pattern

18    12    44    10    9    36    2    6     → 

• 25

• 21

• 30

• 36

• 28

Answer explanation

Explanation:    There are three sequences. The first sequence is formed of terms 1, 4 and 7. The second sequence is formed of terms 2, 5 and 8. The third sequence is formed of terms 3, 6 and 9. The first sequence subtracts 8 to get to the next term. The second sequence subtracts 3 to get to the next term. The third sequence subtracts 8 to get to the next term. Therefore, the next term is 36 - 8 = 28.

Question Type G: Three Sequences - Recurring Pattern