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TNPSC alpha-numeric reasoning practice questions

By the PrepMatic team · Updated 9 Oct 2026 · 3 min read

Alpha-numeric reasoning is the part of the Group 4 reasoning syllabus that works on letters and digits: where a letter sits in the alphabet, how a word is coded, and how a series of letters continues. It rewards a small amount of preparation, because nearly every question depends on the numbers attached to letters. The five questions below cover the typical types. For the whole subject, see TNPSC aptitude and mental ability.

What this topic covers

• Alphabet position: counting left to right and right to left.
• Counting questions: how many times a digit or letter meets a condition.
• Coding and decoding: shifting letters by a fixed number.
• Letter series and pairs: continuing a pattern of letters.

Learn the letter-position table. The mirror pairs always add up to 27 (A is 1 and Z is 26).

A trick to remember: EJOTY are the positions 5, 10, 15, 20 and 25. From any of them you can count to a nearby letter quickly.

Sample questions

Question 1

What is the 5th letter to the right of the 10th letter from the left end of the English alphabet?

• A. N
• B. O
• C. P
• D. Q

Question 2

How many 3s in the sequence 5 3 7 2 8 3 9 4 3 6 are immediately followed by an odd number?

• A. 0
• B. 1
• C. 2
• D. 3

Question 3

If CAT is coded as DBU, then DOG is coded as:

• A. EPH
• B. EPG
• C. ENH
• D. CNF

Question 4

Find the missing pair: AZ, BY, CX, DW, ?

• A. EU
• B. FV
• C. EW
• D. EV

Question 5

Find the next letter in the series: B, E, H, K, N, ?

• A. O
• B. Q
• C. P
• D. R

Answers and explanations

1. B. The 10th letter is J. Five places to its right is the 15th letter: K, L, M, N, O. So the answer is O.
2. C. The 3s are in positions 2, 6 and 9. The first is followed by 7 (odd), the second by 9 (odd) and the third by 6 (even). Two 3s are followed by an odd number.
3. A. Each letter moves one step forward: C to D, A to B, T to U. Applying the same shift: D to E, O to P, G to H, giving EPH. Option D, CNF, is the shift backward.
4. D. The first letters go forward (A, B, C, D, E) and the second go backward (Z, Y, X, W, V), so the missing pair is EV.
5. B. The letters rise by 3 each time: B (2), E (5), H (8), K (11), N (14), and the next is the 17th letter, Q.

How to prepare alpha-numeric reasoning

Memorise the alphabet with numbers using the EJOTY anchors, then practise counting forward and backward from each anchor. Also memorise the mirror rule: a letter's position from the left plus its position from the right is always 27. So the 5th letter from the right is the 22nd from the left, which is V. This resolves "from the right" questions quickly.

For coding questions, test three patterns in order: a fixed forward shift, a fixed backward shift, and a reversed alphabet (A becomes Z, B becomes Y). If none fits, check whether the code uses the sum or product of positions. For counting questions, circle every item that meets the first condition, then check the second condition only on those. This avoids double counting.

Letter series follow the same patterns as TNPSC number series: constant steps, growing steps, alternating steps and interleaved series. If you can do one, you can do the other, so work on both together.

For word problems on position and order, return to TNPSC puzzles practice.

Take the full topic test on PrepMatic

A PrepMatic topic test of about 15 questions and 30 minutes is a fair way to test your speed on letter and digit patterns. Because TNPSC awards 1.5 marks per question, ten reasoning questions are worth 15 marks, and a drill like this is among the cheapest marks to win. The Basic plan includes 5 topic tests at no cost.

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