Number Series, Coding, Odd Man OutMTP Dec 2023 Series IQuestion 2193 of 217
All Questions

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

Options

A12756\displaystyle 12756
B2123\displaystyle 2123
C424\displaystyle 424
D34\displaystyle 34
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Correct Answer

✅ Option b — 2123\displaystyle 2123

All Options:

  • A12756\displaystyle 12756
  • B2123\displaystyle 2123
  • C424\displaystyle 424
  • D34\displaystyle 34

Detailed Solution & Explanation

Let's establish the mathematical pattern linking consecutive terms starting with T1=34\displaystyle T_1 = 34:
- T2=T1×3+3=34×3+3=102+3=105\displaystyle T_2 = T_1 \times 3 + 3 = 34 \times 3 + 3 = 102 + 3 = 105
- T3=T2×4+4=105×4+4=420+4=424\displaystyle T_3 = T_2 \times 4 + 4 = 105 \times 4 + 4 = 420 + 4 = 424
- T4=T3×5+5=424×5+5=2120+5=2125\displaystyle T_4 = T_3 \times 5 + 5 = 424 \times 5 + 5 = 2120 + 5 = 2125 (the series lists 2123\displaystyle 2123, which is incorrect)
- T5=T4×6+6=2125×6+6=12750+6=12756\displaystyle T_5 = T_4 \times 6 + 6 = 2125 \times 6 + 6 = 12750 + 6 = 12756

This pattern (Tn=Tn−1×(n+1)+(n+1)\displaystyle T_n = T_{n-1} \times (n+1) + (n+1)) is perfectly consistent for all terms except 2123\displaystyle 2123, which should be 2125\displaystyle 2125. Therefore, 2123\displaystyle 2123 is the odd man out.

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

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