Reasoning MCQ

                                     Reasoning MCQ – Number Series

Q: What will come next in the series?

2, 9, 28, 65, 126, ?

1. 205

2. 217

3. 210

4. 220

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Answer: 2) 217

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Step-by-step Explanation

First, write the series and find the differences:

2, 9, 28, 65, 126, ?

1. First differences:

9 − 2 = 7

28 − 9 = 19

65 − 28 = 37

126 − 65 = 61

So we get: 7, 19, 37, 61

2. Now find the second differences (difference of the differences):

19 − 7 = 12

37 − 19 = 18

61 − 37 = 24

So: 12, 18, 24

3. Look at these numbers: 12, 18, 24 → these increase by +6 each time.

So next second difference = 24 + 6 = 30

4. Now find the next first difference:

Last first difference = 61

Next first difference = 61 + 30 = 91

5. Finally, find the next term in the series:

Last term = 126

Next term = 126 + 91 = 217

So the correct answer is: 217 ✅

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How to Solve in Short Time (Exam Tip)

1. When series looks complicated, always check differences.

2. If 1st difference is not simple, check 2nd difference.

3. If 2nd difference itself has a pattern (like +6, +6, +6), you can quickly get the next difference and then the next term.

4. Practice this pattern a few times; it’s very common in difficult RRB / SSC / Banking reasoning series.

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Appendix3 Academy