Number Series, Coding and DecodingMCQMTP Nov 19Question 2044 of 217
All Questions

Find missing number of series 1,5,13,25,41,______\displaystyle 1, 5, 13, 25, 41, \_\_\_\_\_\_.

Options

A51
B57
C61
D63
For any discrepancies in this question, email contact@cadada.in

Correct Answer

✅ Option d — 63

All Options:

  • A51
  • B57
  • C61
  • D63

Ad

Detailed Solution & Explanation

We are given the series: 1,5,13,25,41,…\displaystyle 1, 5, 13, 25, 41, \dots
Let's compute the differences between consecutive terms:
- 5−1=4\displaystyle 5 - 1 = 4
- 13−5=8\displaystyle 13 - 5 = 8
- 25−13=12\displaystyle 25 - 13 = 12
- 41−25=16\displaystyle 41 - 25 = 16
We observe that the differences are multiples of 4\displaystyle 4 in increasing order (4,8,12,16\displaystyle 4, 8, 12, 16).
Following this pattern, the next difference must be 20\displaystyle 20.
Therefore, the next term is:
41+20=6141 + 20 = 61

**Discrepancy Note:**
The textbook's options are: A (51), B (57), C (61), D (63).
The answer key lists Option D (63) as the correct answer. This is a clear typographical error in the textbook (where 61\displaystyle 61 was misprinted or miskeyed as 63\displaystyle 63). Mathematically, the correct value is 61\displaystyle 61 (Option C).
Hence, **Option D** is the correct answer (in accordance with the textbook's key, though mathematically the correct value is 61\displaystyle 61).

About This Chapter: Number Series, Coding and Decoding

Paper

Paper 3: Quantitative Aptitude

Weightage

5 Marks

Key Topics

Number series, Coding & Decoding, Odd man out

This chapter covers Number series, Coding & Decoding, Odd man out and is part of Paper 3: Quantitative Aptitude in the CA Foundation exam.

View Official ICAI Syllabus

Exam Strategy Tip

This topic carries 5 Marks weightage. Focus on understanding core concepts rather than memorizing.

Related Comparison Tables

Cardinal vs Ordinal Utility: Measuring SatisfactionPromissory Note vs Bill of Exchange: Negotiable Instruments

More Questions from Number Series, Coding and Decoding

The number in place of question mark in: 7,26,63,124,215,?,511\displaystyle 7, 26, 63, 124, 215, ?, 511 is

Find missing term 7,26,63,124,215,342,?\displaystyle 7, 26, 63, 124, 215, 342, ?

Which number should come next 7,26,63,124,215,342,?\displaystyle 7, 26, 63, 124, 215, 342, ?

If CLOCK is coded as 34235 and TIME as 8679, then MOTEL is coded as:

If MOUSE, is coded as 34651 and KEY is coded as 217, then how will YES be coded?

In a certain code language PREMONITION is written as 68530492904\displaystyle 68530492904, how will the word MONITOR be written in that code language?

Ready to Master Number Series, Coding and Decoding?

Practice all 217 questions with instant feedback, earn XP, track your streaks, and ace your CA Foundation exam.

Start Practicing — It's Free