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Question

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

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

U169

This series pairs a letter with a number in each term, so the sound approach is to split it into two independent trails, one for the letters and one for the numbers, and continue each separately.

The letters run Z, Y, X, W, V, stepping one place backward through the alphabet at every term, so the letter that follows V is U.

The numbers run 4, 9, 25, 49, 121, and each one is a perfect square: \(2^{2}=4\), \(3^{2}=9\), \(5^{2}=25\), \(7^{2}=49\) and \(11^{2}=121\).

Looking at the bases 2, 3, 5, 7, 11, these are the successive prime numbers, so the next base is the prime that follows 11, namely 13.

Squaring that base gives the next number, \(13^{2}=169\).

Combining the two trails, the next letter U joins the next square 169 to form the term U169, which matches one of the choices exactly.

Hence the term that continues the series is U169.

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Similar Questions

  1. 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)

  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)

  3. Select the option that is related to the fifth letter-number cluster in the same way as the second letter-number cluster is related to the first letter-number cluster and fourth letter-number cluster is related to third letter-number cluster.

    (NOTE: Operations should be performed on the whole numbers, without breaking down the numbers 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)

    LW72 : UJ215 :: CA93 : YA278 :: FX103 : ?

  4. 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)

  5. Directions: Select the related letter from the given alternatives.

    MSB: 13- 19- 2:: ?: 4- 10- 18


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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