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Question

In the following question, four letter-number pairs are given. The letter-number on the left side of (-) is related to the letter-number on the right side of (-) with some Logic/Rule/Relation. Three pairs are similar on the basis of same Logic/Rule/Relation. Select the odd one out from the given alternatives. 

(NOTE: Operations should be performed on the whole numbers, without breaking down the number into its constituent digits. E.g.13 -  Operations on 13 such as adding /subtracting /multiplying etc. to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is not allowed)

This question was previously asked in
SSC CHSL 2025 Tier 1 Question Paper (21-Nov-2025) (Shift 1)
The correct answer is

PK320 - OI604

In each pair, compare the two letters and the number on the left with those on the right.

First letter: it always moves one step back in the alphabet, S→R, P→O, E→D, T→S (a shift of −1).

Second letter: it always moves two steps back (cyclically), A→Y, K→I, B→Z, G→E (a shift of −2).

So the letter rule is the same for all four pairs; the distinguishing feature must be the number.

Check the number difference (right number − left number): 581 − 287 = 294, 525 − 231 = 294 and 704 − 410 = 294.

For the pair PK320 − OI604 the difference is 604 − 320 = 284, which is not 294.

Three pairs increase the number by 294 while PK320 − OI604 increases it by only 284, so this is the odd one out.

The odd one out is option 2, PK320 − OI604.

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Similar Questions

  1. What comes next in the following series? Z4, Y9, X25, W49, V121, ?

  2. In the following question, four letter-number pairs are given. The letter-number on the left side of (−) is related to the letter-number on the right side of (−) with some Logic/Rule/Relation. Three pairs are similar on the basis of same Logic/Rule/Relation. Select the odd one out from the given alternatives.

    (NOTE: Operations should be performed on the whole numbers, without breaking down the number into its constituent digits. E.g.13 − Operations on 13 such as adding /subtracting /multiplying etc. to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is not allowed)

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Important Questions from Letter and Number Based

  1. Select the option that is related to the third number in the same way as the second number is related to the first number.

    22 : 441 :: 13 : ?
  2. Select the option that is related to the third number in the same way as the second number is related to the first number.

    31 : 90 :: 43 : ?

  3. Select the option which is related to the third number in the same way as the second number is related to the first number.

    7 : 56 :: 13 : ?

  4. Select the option that is related to the third number in the same way as the second number is related to the first number.

    77 : 11 :: 259 : ?

  5. Select the option that is related to the third number in the same way as the second number is related to the first number.

    15 : 270 :: 13 : ?
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