# Logical Reasoning / Number Series Questions and Answers – IV

19 questions 0n “Logical Reasoning / Number Series Questions and Answers” series Part IV. You can go to homepage to check the other 3 or refer this links Part-I, Part-II etc.

The number series questions are asked every now and then in every competitive exam be it civil services prelims, state civil service exams, Bank PO, RBI, C-TAT etc.

Other Similar Articles:

Odd Man out: Part – I | Part II.

## Questions Section

Q1. Here is the number series to solve, if:
69 + 10 = 5451
13 + 32 = 585
15 + 34 = 735
51 + 71 = ? – what will be the number here?

Answer: 6222 i.e. 51 * (51 + 71)

69 * (69 + 10) = 5451, 13 * (13 + 32) = 585, 15 * (15 + 34) = 735
Logic: The logic is addition of both number multiplied by first number i.e.(69 + 10) * 69 = 5451

Q2. Second question in the series is:
35 + 26 = 315
16 + 32 = -256
41 + 63 = -902
93 + 11 = ? – what will be the number here?

Answer: 7626 i.e. 93 * (93 – 11),

35 * (35 – 26) = 315, 16 * (16 – 32) = -256, 41 * (41 – 63) = -902
Logic: The logic is subtraction of both number multiplied by first number i.e.(35 – 26)*35=315

Q3. Third question in the series is:
52 + 67 = 171
1 + 56 = 58
42 + 28 = 112
65 + 10 = ? – what will be the number here?

Answer: 140 i.e. 65 * 2 + 10

52 * 2 + 67 = 171, 1 * 2 + 56 = 58, 42 * 2 + 28 = 112
Logic: The logic is 2 multiplied by first number plus second number i.e.(52 * 2 + 67) = 171

Q4. What is the next number in the series:

48, 24.0, 12.0, 6.0, ?

Logic: Second number is half of first one, 3rd number is half of second one and so on i.e. 48/2 =24.0, 24.0/2 =12.0, 12.0/2 =6.0 and so on.

Q5. Guess next number in the series:

8, 4.0, ??, 1.0, 0.5

Logic: Second number is half of first one, 3rd number is half of second one and so on i.e.8/2 = 4.0, 4.0/2 = 2.0, 2.0/2 =1.0 and so on.

Q6. Guess next number in the series:

4, 16 , 64 , 256 , ?

Logic: The series is square, cube, ^4 and so on i.e. 4*4 = 16 , 44*4 = 64 etc.

Q7. Guess next number in the series:
6, 7, 9, 12, ?

Ans. 16 i.e. 12 + 4
Second number is (1st number + 1), third number is (2nd number + 2), 4th is (3rd number + 3) and so on.
i.e. 6 + 1 = 7, 7 + 2 = 9, 9 + 3 = 12 and so on.

Q8. What will be the next number in the series:
12, 14, 18, 24, ?

Ans. 32 i.e. 12 + 8
Second number is (1st number + 2), third number is (2nd number + 4), 4th is (3rd number + 6) and so on.
12 + 2 = 14, 14 + 4 = 18, 18 + 6 = 24 and so on.

Q9. Find the missing number in the series:
1,3 ,?? ,13 ,21

Ans. 7 i.e.3 + 4
1 + 2 = 3, 3 + 4 = 7 , 7 + 6 = 13 , 13 + 8 = 21
Logic: Second number is (1st number + 2), third number is (2nd number + 4), 4th is (3rd number + 6) and so on.

Q10. Identify the missing number in the series:
28,31 ,?? ,37 ,40,43

Ans. 34 i.e. 31 + 3
28 + 3 = 31 , 31 + 3 = 34, 34 + 3 = 37, 37 + 3 = 40
Logic: Second number is (1st number + 3), third number is (2nd number + 3), 4th is (3rd number + 3) and so on .i.e. every other number is previous number plus 3.

Q11. Identify the missing number in the series:
16, 19 , ?? , 28 , 34 , 41

Ans. 23 i.e.19 + 4
16 + 3 = 19 , 19 + 4 = 23 , 23 + 5 = 28 , 28 + 6 = 34 , 34 + 7 = 41.
Logic: First number + 3 = 2nd number, second number + 4 = 3rd number, third number + 5 = 4th number and so on.

Q12. Find the missing number in the series:
14 , 14 , ?? , 84 , 336 , 1680

Ans. 28 i.e. 14*2 = 28

14*1 = 14 , 14*2 = 28 , 28*3 = 84 , 84*4 = 336, 336*5 = 1680.
Logic: First number x 1 = 2nd number, second number x 2 = 3rd number, third number x 3 = 4th number and so on.

Q13. Find the missing number in the series:
24,49 ,73 ,?? ,121,145

Ans. 97 i.e. (24*4 + 1) = 97.

24*2 + 1 = 49 , 24*3 + 1 = 73 , 24*4 + 1 = 97 , 24*5 + 1 = 121 , 24*6 + 1 = 145.
Logic: 1st number *2 + 1 = second, 1st number * 3 + 1 = third and so on.

Q14. Find the missing number in the series:
4 , 10 , 15 , ?? , 25 , 30

Ans. 20 i.e. (4^4+4) = 20,

4^2 + 2 = 10, 4^3 + 3 = 15, 4^4 + 4 = 20, 4^5 + 5 = 25, 4^6 + 6 = 30.
Logic: 1st number *2 + 2 = second, 1st number * 3 + 3 = third, 1st number * 4 + 4 = fourth and so on.

Q15. A car crosses a 1600 m long road in 4 minutes. What will be it’s speed in km per hour?

A. 7.92,
B. 12
C. 14.4
D. 24

Answer: 24.0 km/h i.e. [(1600/1000) / (4/60)]
Logic: Converting 1600 to kilometer by dividing it by 1000 and converting 4 to hour by dividing it by 60 and dividing both.

Q16. Next number in the series is:

8 , 11 , 9 , 12 , 10 , ??

Ans: 13 i.e. 10 + 3 = 13
8 , 8 + 3 = 11 , 11 – 2 =9 and so on i.e. +3 and then -2 in alternate numbers.
Logic: This is a simple alternating addition and subtraction series. In the first pattern, 3 is added; in the second, 2 is subtracted and so on.

Q17. Next number in the series is:

20 , 18 , 14 , 12 , 8 , ??

Ans: 6 i.e. 8 – 2 = 6
20 , 20 – 2 = 18 , 18 – 4 =14 and so on i.e. -2 and then -4 in alternate numbers.
Logic: This is a simple alternating subtraction series. In the first pattern, 2 is subtracted; in the second, 4 is subtracted and so on.

Q18. Next number in the series is:

28 , 27 , 29 , 28 , 30 , ??

Ans: 29 i.e. 30 – 1 = 29
28 , 28 – 1 = 27 , 27 + 2 =29 and so on i.e. -1 and then +2 in alternate numbers.
Logic: This is a simple alternating subtraction series. In the first pattern, 1 is subtracted; in the second, 2 is added and so on.

Q19. Next number in the series is:

30 , 30 , 19 , 19 , 8 , ??

Ans: 8 i.e. 19 – 11 = 8
30 , 30 , 30 -11 = 19 , 30 -11 = 19 and so on i.e. same number is repeated twice and then 11 is subtracted from it..
Logic: This is a simple alternating subtraction series. After repeating same number twice 11 is subtracted from it.