# Number Series Logical Reasoning Questions and Answers Part 4

13. What comes next?
7 8 16 43 ?

a. 107
b. 96
c. 86
d. 103

Explanation:

8 - 7 = 1
16 - 8 = 8
43 -16 = 27
1, 8, 27 are cubes of 1, 2 and 3
So next difference must be cube of 4
So, ? - 43 = 43 = 64
So, ? = 64+43 = 107

14. 20, 4, 24, 64, 30, 196, 38, ?

a. 361
b. 400
c. 420
d. 441

Explanation:

Here we see ups and downs in the series so there is a chance of 2 separate series
We can have 20 24 30 38 as one series
And 4 64 196 as other series.
Both series occur alternately so next term has to be of the second series.
In first series difference is
24 - 20 = 4
30 - 24 = 6
38 - 30 = 8
So, difference increases by 2
In second series, We see they are squares i.e. 22, 82, 142
8-2 = 6
14-8 = 6
So next number, ? - 14 has to be = 6
So, ? = 14+6 = 20
So next term is 202 = 400

15. CZ , HU, NQ, ?

a. VN
b. UN
c. TM
d. VO

Explanation:

Alphabet Series - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Here the first letters of the terms is C, H, N
H is 5th letter from C
N is 6th letter from H
So next has to be 7th letter from N i.e. V

In the second letters we have Z, U, Q
U is 5th letter from Z
Q is 4th letter from U
So next has to be 3rd letter from Q i.e. N

16. What is the next term?
AN13 , BZ24 , CO12 , DY21 , ?

a. EP18
b. EX18
c. FX10
d. EP11

Explanation:

Alphabets and their positions

 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

• First letters of each term are A, B, C, D. So, in answer first letter should be E.
• Second letters are N, Z, O, Y. We can observe there are alternately 2 series N, O, etc. and Z, Y, etc.
• So next has to be P which comes after O.
• In many alphanumeric series, numbers are mostly related to the positions of the letters.
• See the first term, A has position 1. N has position 14. 14 -1 = 13
• Similarly, B has position 2. Z has 26. 26 - 2 = 24
• In ? we have EP. E has position 5. P has 16. 16 - 5 = 11