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All questions of Alphabetical and Number Series for Civil Engineering (CE) Exam

Look at this series: 53, 53, 40, 40, 27, 27, ... What number should come next?
  • a)
    12
  • b)
    14
  • c)
    27
  • d)
    53
Correct answer is option 'B'. Can you explain this answer?

Vikas Choudhury answered
Explanation:
In this series, each number is repeated, and then 13 is subtracted to arrive at the next number.
The pattern can be described as follows:
● The first number is 53, and it is repeated.
● Then, 13 is subtracted from the first number to get the second number, which is 40.
● The second number is then repeated.
● Again, 13 is subtracted from the second number to get the third number, which is 27.
● The third number is repeated.
● Finally, 13 is subtracted from the third number to get the next number in the series, which is 14.
Therefore, the answer is 14, as it follows the established pattern in the series.

You can study more about Number Series through the document: 
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Look at this series: 3, 4, 7, 8, 11, 12, ... What number should come next?
  • a)
    7
  • b)
    10
  • c)
    14
  • d)
    15
Correct answer is option 'D'. Can you explain this answer?

Alok Verma answered
This alternating addition series begins with 3; then 1 is added to give 4; then 3 is added to give 7; then 1 is added, and so on.

Look at this series: 2, 1, (1/2), (1/4),...so on. What number should come next?
  • a)
    (1/3)
  • b)
    (1/8)
  • c)
    (2/8)
  • d)
    (1/16)
Correct answer is option 'B'. Can you explain this answer?

Varun Kapoor answered
This is a simple division series, each number is one-half of the previous number.
In other terms to say, the number is divided by 2 successively to get the next result.
► 4/2 = 2
► 2/2 = 1
► 1/2 = 1/2
► (1/2) / 2 = 1/4
► (1/4) / 2 = 1/8 and so on.

Look at this series: 7, 10, 8, 11, 9, 12, ... What number should come next?
a)7
b)10
c)12
d)13
Correct answer is 'B'. Can you explain this answer?

Raghavendra Sharma answered
This is a simple alternating addition and subtraction series. In the first pattern, 3 is added; in the second, 2 is subtracted.

Look at this series: 8, 22, 8, 28, 8, ... What number should come next?
  • a)
    9
  • b)
    29
  • c)
    32
  • d)
    34
Correct answer is option 'D'. Can you explain this answer?

Bijoy Pillai answered
This is a simple addition series with a random number, 8, interpolated as every other number. In the series, 6 is added to each number except 8, to arrive at the next number.

Directions to Solve
Choose the correct alternative that will continue the same pattern and replace the question mark in the given series.
Question -
13, 35, 57, 79, 911, ?
  • a)
    1110
  • b)
    1112
  • c)
    1113
  • d)
    1315
Correct answer is option 'C'. Can you explain this answer?

Gargi Kulkarni answered
The terms of the given series are numbers formed by joining together consecutive
odd numbers in order i.e. 1 and 3, 3 and 5, 5 and 7, 7 and 9, 9 and 11, .....
So, missing term = number formed by joining 11 and 13 = 1113.

Directions to Solve
Choose the correct alternative that will continue the same pattern and replace the question mark in the given series.
Question -
In the series 3, 9, 15, ...... what will be the 21st term?
  • a)
    117
  • b)
    121
  • c)
    123
  • d)
    129
Correct answer is option 'C'. Can you explain this answer?

Ankita Dey answered
Pattern Analysis:
To find the pattern in the given series, we need to observe the difference between consecutive terms.

The difference between the first and second terms is 9 - 3 = 6.
The difference between the second and third terms is 15 - 9 = 6.

From the above observations, we can see that the difference between consecutive terms is constant and equal to 6.

Pattern:
The pattern can be represented as:
3, 9, 15, 21, ...

Finding the 21st Term:
To find the 21st term in the series, we need to determine the value by adding the constant difference to the last term.

The last term in the given series is 15.
Using the pattern, we can find the 21st term as follows:

15 + (6 x 15) = 15 + 90 = 105.

Therefore, the 21st term in the series is 105.

Explanation of Correct Answer:
The correct answer is option 'C' (123).

The given options are:
a) 117
b) 121
c) 123
d) 129

To confirm the correct answer, let's check if the 21st term is 123 by using the pattern.

Starting from the first term (3), we can calculate the terms in the series as follows:
3, 9, 15, 21, 27, 33, 39, 45, 51, 57, 63, 69, 75, 81, 87, 93, 99, 105, 111, 117, 123.

As we can see, the 21st term is indeed 123, which matches option 'C'.

Hence, the correct answer is option 'C' (123).

Directions to Solve
Choose the correct alternative that will continue the same pattern and replace the question mark in the given series.
Question -
240, ?, 120, 40, 10, 2
  • a)
    180
  • b)
    240
  • c)
    420
  • d)
    480
Correct answer is option 'B'. Can you explain this answer?

Madhavan Nambiar answered
Understanding the Series
To solve the series: 240, ?, 120, 40, 10, 2, we need to identify the pattern between the numbers.
Identifying the Pattern
- First Difference:
- From 240 to 120, we see that 240 is halved to give 120. This indicates a division by 2.
- Second Difference:
- Continuing the pattern, 120 to 40 also shows halving: 120 / 3 = 40.
- Third Difference:
- Again, 40 to 10 is another halving: 40 / 4 = 10.
- Fourth Difference:
- Finally, 10 to 2 follows the same pattern: 10 / 5 = 2.
Inferring the Missing Value
To find the missing value, we can observe that the series involves halving the numbers sequentially while increasing the divisor (2, 3, 4, 5).
- Before 120, the missing number should be halved by 2 as follows:
- 240 divided by a number should yield the next number in the series.
- If we apply the same logic backward:
- The number that comes before 120, when divided by 2, gives 120.
- Thus, the number must be:
- 240 / (2) = 120.
- The immediate previous number to 240, which fits into our series pattern, is indeed 240 itself.
Conclusion
Therefore, the correct alternative that continues the pattern is:
- Correct Answer: 240 (Option B).
This clearly fits into the established pattern of halving the previous number, confirming that Option B is the right answer.

Look at this series: 1, 3, 6, 10, 15...so on. What number should come next?
  • a)
    21
  • b)
    22
  • c)
    20
  • d)
    23
Correct answer is option 'A'. Can you explain this answer?

EduRev CLAT answered
It is a triangular number series forming a triangular pattern.
► 1 = 1,
► 1+2 = 3,
► 1+2+3 = 6,
► 1+2+3+4 = 10,
► 1+2+3+4+5 = 15,
► 1+2+3+4+5+6 = 21.

Chapter doubts & questions for Alphabetical and Number Series - RRB JE Mock Test Series for Civil Engineering (CE) 2025 2025 is part of Civil Engineering (CE) exam preparation. The chapters have been prepared according to the Civil Engineering (CE) exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for Civil Engineering (CE) 2025 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.

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