Directions:(1-5) Find the next term in the series.

1. 10, 15, 25, 35, 55, ?

Ans:5
The pattern 5 being multipled by consecutive prime numbers:

5 x 2 = 10

5 x 3 = 15

5 x 5 = 25

5 x 7 = 35

5 x 11 = 55

5 x 13 = 65

 

2. 19, 28, 39, 52, 67, ?

Ans:3
The pattern is as follows:

2 x 5 + 9 = 19

3 x 6 + 10 = 28

4 x 7 + 11 = 39

5 x 8 + 12 = 52

6 x 9 + 13 = 67

7 x 10 + 14 = 84

 

3. 265, 233, 203, 175, 149, ?

Ans:5
The pattern is as follows:

162 + 9 = 265

152 + 8 = 233

142 + 7 = 203

132 + 6 = 175

122 + 5 = 149

112 + 4 = 125

 

4. 727, 509, 339, 211, 119, ?

Ans:2
The pattern is as follows:

93 – 2 = 727

83 – 3 = 509

73 – 4 = 339

63 – 5 = 211

53 – 6 = 119

43 – 7 = 57

 

5. 7, 21, 49, 91, 147, ?

Ans:4
The pattern is as follows:

7 + 14 x 1 = 21

21 + 14 x 2 = 49

49 + 14 x 3 = 91

91 + 14 x 4 = 147

147 + 14 x 5 = 217

 

Directions:(6-10) Find the wrong term in the series given below.

6. 43, 55, 85, 143, 273, 455

Ans:4
The pattern adds the number to product of a prime number and the number following it:

43 + 3 x 4 = 55

55 + 5 x 6 = 85

85 + 7 x 8 = 141

141 + 11 x 12 = 273

273 + 13 x 14 = 455

 

7. 92, 112, 134, 158, 186

Ans:1
The pattern is as follows:

92 + 11 = 92

102 + 12 = 112

112 + 13 = 134

122 + 14 = 158

132 + 15 = 184

 

8. 113, 116, 122, 126, 140, 162

Ans:2
The series adds the product of the digits to the previous number:

113 + 3 = 116

116 + 6 = 122

122 + 4 = 126

126 + 12 = 138

138 + 24 = 162

 

9. 12585, 4229, 1425, 483, 165, 57

Ans:4
The pattern is shown below:

12585/3 + 25 = 4227

4227/3 + 24 = 1425

1425/3 + 23 = 483

483/3 + 22 = 165

165/3 + 21 = 57

 

10. 3.2, 6.3, 8.4, 10.0, 11.6

Ans:5
The pattern is shown below:

√10= 3.2

√40= 6.3

√70= 8.4

√100= 10.0

√130= 11.4

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11 thoughts on “Number Series”

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