Find odd man out: 34, 105, 424, 2123, 12756 .

Option b: 2123. Solution: Let's establish the mathematical pattern linking consecutive terms starting with T1 = 34 : - T2 = T1 × 3 + 3 = 34 × 3 + 3 = 102 + 3 = 105 - T3 = T2 × 4 + 4 = 105 × 4 + 4 = 420 + 4 = 424 - T4 = T3 × 5 + 5 = 424 × 5 + 5 = 2120 + 5 = 2125 (the series lists 2123 , which is incorrect) - T5 = T4 × 6 + 6 = 2125 × 6 + 6 = 12750 + 6 = 12756 This pattern ( Tn = Tn-1 × (n+1) + (n+1) ) is perfectly consistent for all terms except 2123 , which should be 2125 . Therefore, 2123 is the odd man out. Hence, Option B is the correct answer.

Find odd man out: $34, 105, 424, 2123, 12756$.

The correct answer is Option b: $2123$. Let's establish the mathematical pattern linking consecutive terms starting with $T_1 = 34$: - $T_2 = T_1 \times 3 + 3 = 34 \times 3 + 3 = 102 + 3 = 105$ - $T_3 = T_2 \times 4 + 4 = 105 \times 4 + 4 = 420 + 4 = 424$ - $T_4 = T_3 \times 5 + 5 = 424 \times 5 + 5 = 2120 + 5 = 2125$ (the series lists $2123$, which is incorrect) - $T_5 = T_4 \times 6 + 6 = 2125 \times 6 + 6 = 12750 + 6 = 12756$ This pattern ($T_n = T_{n-1} \times (n+1) + (n+1)$) is perfectly consistent for all terms except $2123$, which should be $2125$. Therefore, $2123$ is the odd man out. Hence, **Option B** is the correct answer.

Number Series, Coding and DecodingMCQMTP Dec 2023 Series IQuestion 2193 of 217

All Questions

Find odd man out: $\displaystyle 34, 105, 424, 2123, 12756$ .

Options

\displaystyle 12756

\displaystyle 2123

\displaystyle 424

\displaystyle 34

For any discrepancies in this question, email contact@cadada.in

Correct Answer

✅ Option b — $\displaystyle 2123$

All Options:

A $\displaystyle 12756$
B $\displaystyle 2123$
C $\displaystyle 424$
D $\displaystyle 34$

Detailed Solution & Explanation

Let's establish the mathematical pattern linking consecutive terms starting with

\displaystyle T_1 = 34

:
-

\displaystyle T_2 = T_1 \times 3 + 3 = 34 \times 3 + 3 = 102 + 3 = 105

\displaystyle T_3 = T_2 \times 4 + 4 = 105 \times 4 + 4 = 420 + 4 = 424

\displaystyle T_4 = T_3 \times 5 + 5 = 424 \times 5 + 5 = 2120 + 5 = 2125

(the series lists

\displaystyle 2123

, which is incorrect)
-

\displaystyle T_5 = T_4 \times 6 + 6 = 2125 \times 6 + 6 = 12750 + 6 = 12756

This pattern (

\displaystyle T_n = T_{n-1} \times (n+1) + (n+1)

) is perfectly consistent for all terms except

\displaystyle 2123

, which should be

\displaystyle 2125

. Therefore,

\displaystyle 2123

is the odd man out.

Hence, **Option B** is the correct answer.

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.

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Find odd man out: 34,105,424,2123,12756\displaystyle 34, 105, 424, 2123, 1275634,105,424,2123,12756.