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Alphanumeric reasoning

By TNPSC Guide editorial team · Last updated:

Source: கணக்கு, எட்டாம் வகுப்பு, தமிழ் வழி (Mathematics, Standard VIII, Tamil medium; Samacheer Kalvi) (8ஆம் வகுப்புக் கணக்கு, இயல் 7 (7.7 குறியாக்கவியல்), பக்கம் 262-269, விடைகள் பக்கம் 288; TNPSC வினாத்தாள்கள் CCS4T/2022 பக்கம் 45, 77, CCSE4GT/2024 பக்கம் 87, 91, CCSEIVGT/2025 பக்கம் 82, 122-123 (வினாத்தாள் விதிகள் மட்டும்))

PYQ (2016-2025 papers)

Free questions

  1. Question 1

    In the textbook's +4 table (e is A, f is B, ..., d is Z), which word is the secret fec?

    1. A. JIG
    2. B. CBZ
    3. C. AZX
    4. D. BAY
    Answer and explanation

    Correct answer: D. BAY

    4 places back: f → B, e → A; from c go b, a, then wrap to the end of the alphabet, z, y, so c → Y; fec is BAY.

    Source: கணக்கு, எட்டாம் வகுப்பு, தமிழ் வழி (Mathematics, Standard VIII, Tamil medium; Samacheer Kalvi) (இயல் 7 தகவல் செயலாக்கம் (7.7 குறியாக்கவியல்), p. 263 (PDF p. 269))

  2. Question 2

    What is cryptology?

    1. A. A table that gives numbers to letters
    2. B. The science of communicating in a secure form
    3. C. A method of writing each word backwards
    4. D. A method of writing the alphabet backwards
    Answer and explanation

    Correct answer: B. The science of communicating in a secure form

    Cryptology is the science of communicating in a secure form; military, political and private communication all need information security.

    Source: கணக்கு, எட்டாம் வகுப்பு, தமிழ் வழி (Mathematics, Standard VIII, Tamil medium; Samacheer Kalvi) (இயல் 7 தகவல் செயலாக்கம் (7.7 குறியாக்கவியல்), p. 262 (PDF p. 268))

  3. Question 3

    Consider the following statements on cryptology. 1. The true message in its usual form is the plain text. 2. Cipher text is usually written in capital letters. 3. Plain text is usually written in capital letters. Which of these are correct?

    1. A. 1 and 2 only
    2. B. 1 only
    3. C. 2 and 3 only
    4. D. 1, 2 and 3
    Answer and explanation

    Correct answer: A. 1 and 2 only

    The message in its usual form is the plain text; cipher text is usually in capitals and plain text in small letters; so 1 and 2 are correct and 3 is wrong. (The textbook's own +4 table in Example 7.8 does the opposite, with the secret letters small and their meanings in capitals; statement 2 gives the usual rule.)

    Source: கணக்கு, எட்டாம் வகுப்பு, தமிழ் வழி (Mathematics, Standard VIII, Tamil medium; Samacheer Kalvi) (இயல் 7 தகவல் செயலாக்கம் (7.7 குறியாக்கவியல்), p. 262 (PDF p. 268))

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