Number Series : 10 Important Questions

One of the number in the series is wrong, find the wrong number in the series :-

Ques 1.

36 , 43 , 49 , 54 , 60 , 61 , 63 , 64

(a) 60

(b) 63

(c) 54

(d) 43

Ques 2.

3 , 10 , 41 , 206 , 1236 , 8660

(a) 10

(b) 41

(c) 206

(d) 1236

Ques 3.

12 , 20 , 38 , 42, 56 , 72 

(a) 20

(b) 38

(c) 56

(d) 72

Ques 4.

5040 , 840 , 160 , 42 , 14 , 7 

(a) 7

(b) 160

(c) 14

(d) 840

Ques 5.

81, 64 , 49 , 35 , 25 , 16

(a) 64

(b) 35

(c) 35

(d) 16

Ques 6.

625 , 125 , 25 , 5 , 0

(a) 0

(b) 125

(c) 5

(d) 625

Ques 7.

25 , 19 , 17 , 13 , 11 ,7

(a) 25 

(b) 17

(c) 13

(d) 7

Ques 8.

3 , 10 , 27 , 4 , 16 , 64 , 5 , 25 , 125

(a) 25

(b) 16

(c) 10

(d) 3

Ques 9.

13, 39 , 195 , 1363 , 12285 

(a) 13

(b) 1363

(c) 39

(d) 195

Ques 10.

2 , 3, 6, 18 , 108 , 1942

(a) 6

(b) 18

(C) 1942

(d) 3

solutions :

Ans 1. The difference between two consecutive number is decreasing  by 1 at each step.

        ∴ 58 should be in place of 60.

Ans 2.The sequence followed in this series is :

                     3 x 3 + 1 = 10

                     10 x 4 + 1= 41

                    41 x 5 + 1 = 206

                   206 x 6 +1 = 1237; and 

       ∴ 1237 shuold be in place of 1236.

Ans 3. The sequence followed  in this series is :

            3 x 4  = 12

            4 x 5  = 20

            5 x 6  = 30 

            6 x 7  = 42

            7 x 8  = 56

            8 x 9  = 63

∴ 30 should be in place of 38.

Ans 4.The numbers in the series are divided by numbers in reverse  order starting from 6 to get the next number .

      ∴ 168 should be in place of 32.

Ans 5. The sequence is the  square of the number in decreasing order  starting from 9, i.e

            92  = 9 x 9 = 81

            82  = 8 x 8 = 64

            72  = 7 x 7 = 49

            62  = 6 x 6 = 64

            52  = 5 x 5 = 25

            42  =  4 x 4 = 16

   ∴ 36 should be in place of 35

Ans 6 . The number in the series are divided by 5 to get the next number .

      ∴ 1 should be in place of 0 digit.

Ans 7. Other numbers are prime numbers.

Ans 8. The sequence of the series is formed by a  number ,its square , its cube, then the next  number is natural order , i.e.,

         31  = 3

         32  = 3 x 3 = 9

         33  = 3  x 3 x 3 = 27

    next number :

          41 = 4 

          42 = 4 x 4  = 16 

          43 =  4 x 4 x 4 = 64

    next number :

           51 = 5

           52  = 5 x 5 = 25

           53  = 5 x 5 x 5 = 125

 ∴   9 should be in place of 10 .

Ans 9. In this series the numbers are multiplied by odd numbers in natural order numbers in natural order starting from 3, i .e.

    ∴ 1365 should be in place of 1363

Ans 10. The numbers in the series are the product of two numbers preceding it , i.e.

   ∴ 1944 should be in place 0f 1942.