Quantitative Aptitude · Number Series, Coding-Decoding and Odd Man Out

Odd Man Out: Letters and Words

Updated 1 October 2026 · Fact-checked

Odd man out means finding the one item that does not follow the pattern shared by the others. For letters, check alphabet positions, gaps, vowel counts and mirror pairs. For words, check category, meaning, spelling or letter pattern. Find a rule that fits three options exactly and breaks for one, then pick that one.

Understand Odd Man Out: Letters and Words

In an odd man out question, you get a set of items, usually four options. Three share a hidden property. One does not. Your job is to find the property and pick the item that breaks it.

With letter groups, the property is usually numeric. Convert each letter to its position (A = 1, B = 2, ... Z = 26). Then look at the gaps between letters, the sum of positions, whether the group runs forward or backward, or how many vowels it holds.

With words, the property is usually about meaning or form. Meaning-based sets include category (fruits, rivers, metals), function (things that fly) or relation. Form-based sets include the number of letters, the number of vowels, a repeated letter, or a word that is spelt the same in reverse.

The key idea is that the rule must fit all three 'normal' items exactly and fail for only one. If your rule fits two or fits none, it is the wrong rule. Try the next one.

This is a Paper 3 objective topic. The questions are quick if you check rules in a fixed order. They become slow if you guess.

Key formulas to remember

Alphabet position: A=1, B=2, C=3, ... M=13, N=14, ... Z=26; Memorise M = 13 and N = 14. Every other position can be reached from these two quickly.
Opposite (mirror) letter: Position of opposite letter = 27 − position of the letter; A pairs with Z, B with Y, M with N. Two letters that are mirror pairs have positions adding up to 27.
Vowels: Vowels = A, E, I, O, U; All other letters are consonants. Count vowels in each group or word when positions give no pattern.
Gap between letters: Gap = position of next letter − position of current letter; Compare the gaps within each group. A group with different gaps from the others is often the odd one.
Sum of positions: Group value = sum of positions of its letters; Use it for pairs and triples when gaps do not match. Check whether the sums are equal, all even, or all multiples of some number.

How to solve Odd Man Out: Letters and Words questions

Use this order for any letter or word odd man out question. It stops you from jumping at the first idea.

1Read all four options once. Note whether they are letter groups, real words or meaningless strings.
2If they are real words, ask first: do three belong to one category or meaning? If yes, the fourth is the answer.
3If meaning gives no split, check form: number of letters, number of vowels, repeated letters, first and last letters.
4If they are letter groups, write the position of each letter under it.
5Find the gaps inside each group (second − first, third − second). Check forward or backward direction.
6If gaps do not split the options, check the sum of positions, the vowel count, and mirror pairs (positions adding to 27).
7Confirm your rule: it must hold for exactly three options and fail for one. If it fails this test, drop it and try the next rule.
8Mark the odd option. Do not spend time proving the other three beyond a quick check.

Quickest way: Gap-first, then category

When to use it: Use it when time is short. Aim for about 30 to 40 seconds per question in Paper 3.

For words, spend 5 seconds on category. A clear category split settles it at once.
For letter groups, compute only the gaps of each group first. Do not write all positions unless needed.
Look at which group has a different gap pattern. Check that the other three agree. Done.
If gaps all match, move to the sum of positions, then vowel count.
Use option elimination: if two options clearly follow the same rule as each other and a third, the remaining one is odd.
If no rule appears in about a minute, skip and return later. A wrong answer costs 0.25 marks, so do not guess blindly.

Common mistakes in Odd Man Out: Letters and Words

Picking an answer after finding one rule that fits only two options.
A partial pattern looks convincing and you stop checking.
Fix: Test the rule on all four options. It must fit exactly three and fail for one.
Miscounting alphabet positions, especially after M.
You count from A on your fingers and slip.
Fix: Anchor on M = 13 and N = 14. For letters after N, count forward from N, or use 27 − position of the mirror letter.
Checking only the gaps and ignoring direction.
A group such as a backward run looks like it has the same gap size.
Fix: Write the sign of each gap. A step of +2 and a step of −2 are different patterns.
Choosing a word by personal preference in meaning, such as picking the 'least common' item.
You do not look for a strict category.
Fix: State the category in a few words, for example 'all are fruits'. Choose the one that clearly does not belong.
Ignoring form-based rules when words share a category.
When all four words look related, you assume the question is faulty.
Fix: Check letter count, vowel count and spelling features. Check also a finer category, such as one river among lakes.
Spending too long on one hard set.
Trying every possible rule feels productive.
Fix: Set a limit of about a minute. Skip and return if time remains, since wrong answers carry negative marking.

Worked examples

Example 1

Find the odd one out: (A) BDF (B) GIK (C) LNP (D) QSV

Show the solution

Convert to positions: BDF = 2, 4, 6. GIK = 7, 9, 11. LNP = 12, 14, 16. QSV = 17, 19, 22.
Find gaps: BDF = +2, +2. GIK = +2, +2. LNP = +2, +2. QSV = +2, +3.
Three groups have equal gaps of +2. QSV breaks the pattern at the last step.

Answer: (D) QSV

Example 2

Find the odd one out: (A) Mango (B) Apple (C) Potato (D) Banana

Show the solution

Check category first. Mango, apple and banana are fruits.
Potato is a vegetable (a root tuber), so it does not fit the fruit category.
Check that the rule is clean: it fits three options and fails for exactly one.

Answer: (C) Potato

Example 3

Find the odd one out: (A) AZ (B) DW (C) FU (D) HT

Show the solution

Write positions: A = 1, Z = 26. D = 4, W = 23. F = 6, U = 21. H = 8, T = 20.
Find the sums: AZ = 1 + 26 = 27. DW = 4 + 23 = 27. FU = 6 + 21 = 27. HT = 8 + 20 = 28.
AZ, DW and FU are mirror pairs, since each sums to 27. HT sums to 28, so it is not a mirror pair. (The mirror of H is S.)

Answer: (D) HT

Exam tips

Always start with the easiest check: category for words, gaps for letter groups. Most questions are solved in the first check.
Learn the positions of vowels (A=1, E=5, I=9, O=15, U=21). They help with vowel-pattern questions.
Remember that mirror pairs add up to 27. This makes opposite-letter sets quick to spot.
In an MCQ paper with 0.25 negative marking, skip a set when you find no rule after about a minute. Come back if time remains.
Practise with mixed sets of words, letter groups and numbers so that you can switch between rule types quickly.

Practice questions from Number Series, Coding-Decoding and Odd Man Out

Odd Man Out: Letters and Words: frequently asked questions

What is odd man out in logical reasoning?

It is a question type where you pick the one item that does not share the common property of the others. The items may be letters, words or numbers. You must find the rule first, then choose the item that fails it.

How do I find the rule for letter groups?

Write the alphabet position of each letter and look at the gaps. If gaps match in all groups, check the sum of positions, then the vowel count and mirror pairs. The right rule fits three groups and fails one.

What if all the words seem to belong to the same category?

Look for a narrower category or a form-based rule. Check the letter count, the number of vowels, repeated letters or the starting letter. One word will usually differ on one of these.

Is there negative marking for this topic in CA Foundation?

Yes. Paper 3 Quantitative Aptitude is an objective paper with a negative marking of 0.25 marks per wrong answer. Skip a question if you cannot find a rule that fits exactly three options.