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Number series problems

 

Number Series

 

1.         2, 3, 5, 7, 11, 13

            (a) 15                           (b) 17                           (c) 18                           (d) 19

Ans.     (b)  The given series is prime number series. The next prime number is 17.

2.         2, 5, 11, 17, 23, ....., 41

            (a) 29                           (b) 31                           (c) 37                           (d) 39

Ans.     (b)  The prime numbers are written alternately.

3.         2, 5, 8, 11, 14, 17, ....., 23.

            (a) 19                           (b) 21                           (c) 20                           (d) 18

Ans.     (c)  The difference between the numbers is 3. (17 + 3 = 20)

4.         45, 38, 31, 24, 17, ....., 3.

            (a) 12                           (b) 14                           (c) 10                           (d) 9

Ans.     (c)  The difference between the numbers is 7. (17 - 7 = 10)

5.         2, 6, 18, 54, 162, ...., 1458.

            (a) 274                         (b) 486                         (c) 1236                       (d) 1032

Ans.     (b)  The numbers are multiplied by 3 to get next number. (162 x 3 = 486).

 

6.         0, 3, 8, 15, 24, 35, 48, .......

            (a) 60                           (b) 62                           (c) 63                           (d) 64

Ans.     (c)  The series 12 - 1, 22 - 1, 32 - 1, etc. The next number is 82 - 1 = 63.

 

7.       0, 7, 26, 63, 124, ....., 342.

            (a) 128                         (b) 300                         (c) 240                         (d) 215

Ans.     (d)  The series is 13 - 1, 23 - 1, 33 - 1, etc. The missing numebr is 63 - 1 = 215.

 

 

 

 

8.       2, 12, 36, 80, 150, .....

            (a) 250                         (b) 252                         (c) 276                         (d) 300

Ans.     (b)  The series is 13 + 12, 23 + 22, 33 + 32 etc. 

 

9.         1, 1, 2, 4, 3, 9, 4, 16, 5, 25, ...., ....

            (a) 6, 36                       (b) 6, 30                       (c) 7, 36                       (d) 7, 30

Ans.     (a)  The series is 1, 12, 2, 22, 3, 32, etc. The missing numbers are 6, 62 i.e. 6, 36.

 

10.         2, 4, 3, 9, 5, 25, 7, 49, ......, .........

            (a) 9, 81                       (b) 11, 121                   (c) 10, 100                   (d) 12, 144

Ans.     (b)  The series is 2, 22; 3, 32; 5, 52; 7, 72.

            The next prime number is 11. The missing number is 11, 112 i.e., 11 and 121.