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4th Std Scholarship · Intelligence Test

Odd one out

5 concepts · 40 practice questions with answers · Free to read

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The odd one out among words

From daily life

Mother packs a mango, a banana, an apple and a potato in the tiffin. We say at once, "The potato is different, it is a vegetable." Three things belong to one group and one is different; we notice this every day. This is spotting the odd one out.

Simple definition

A criterion is the common quality that joins a group. The one that does not meet the criterion that the others meet is the odd one out. First find the criterion, then pick the one that does not fit.

How to recognise criteria

GroupCriterionOdd one out
Mango, banana, apple, potatoFruitsPotato (a vegetable)
Cow, buffalo, goat, peacockFour-legged animalsPeacock (a bird)
Pen, pencil, chalk, scissorsThings to write withScissors
1
Rule 1

First find the common quality (criterion) that ties three of them together.

  • E.g. Rose, jasmine, lotus, mango. The first three are flowers. Criterion : flowers. Mango is different.
2
Rule 2

See whether they belong to one class (fruits, vegetables, animals, birds, vehicles).

  • E.g. Cow, buffalo, dog, sparrow. The first three have four legs. The sparrow is a bird, so it is different.
3
Rule 3

Look at the use or the job.

  • E.g. Pen, pencil, chalk, scissors. The first three are used for writing. Scissors for cutting. So scissors is different.
4
Rule 4

Look at where they go, where they live, where they are found.

  • E.g. Bus, truck, car, ship. The first three go on the road. The ship goes on water. So the ship is different.
Example 1 · easy

Apple, banana, carrot, grapes. Which is different?

  1. Apple, banana and grapes are fruits.
  2. Carrot is a vegetable. Answer : Carrot.
Example 2 · medium

Lion, tiger, cheetah, deer. Which is different?

  1. Lion, tiger and cheetah are meat-eaters.
  2. The deer is a plant-eater. Answer : Deer.
Example 3 · exam type

Crow, sparrow, peacock, bat. Which is different?

  1. Crow, sparrow and peacock are birds. They have feathers.
  2. The bat is not a bird, it is a mammal. Answer : Bat.
Remember

First decide, "How are the three alike?" Then see whether the fourth fits.

Common mistake

Grabbing the first difference you see. First check which is the real criterion that joins the three words.

Shortcut

Memory clue : "How are the three alike? The one that is not, is odd."

Shortcut

If no criterion comes to mind, check class, use, place, and colour-shape one by one.

Spot the difference

CriterionExample
ClassFruits, vegetables, animals, birds
UseWriting, cutting, eating
PlaceWater, land, air

Practice questions

Easy
  1. 1Red, blue, yellow, Monday. Which is different?
  2. 2Table, chair, cupboard, banana. Which is different?
  3. 3Mumbai, Pune, Nagpur, Ganga. Which is different?
Medium
  1. 4Mango, guava, banana, brinjal. Which is different?
  2. 5Sunday, Monday, Tuesday, March. Which is different?
  3. 6Rice, wheat, jowar, moong. Which is different?
Challenging
  1. 7Parrot, pigeon, kite, penguin. Which is different?
  2. 8Elephant, horse, cow, fish. Which is different?
Show answers (try them yourself first)
  1. 1Monday (a weekday; the others are colours).
  2. 2Banana (a fruit; the others are furniture).
  3. 3Ganga (a river; the others are cities).
  4. 4Brinjal (a vegetable; the others are fruits).
  5. 5March (a month; the others are weekdays).
  6. 6Moong (a pulse; the others are cereals).
  7. 7Penguin (cannot fly; the others fly).
  8. 8Fish (lives in water; the others are land animals).

The odd one out among numbers

From daily life

When we recite the table of 6 we say 6, 12, 18, 24. If 25 comes in, it sounds wrong at once, because 25 is not in the table of 6. Numbers have many criteria : even-odd, tables, squares, primes.

Simple definition

In a group of numbers three numbers share one quality and the fourth does not. That fourth is the odd one out.

Criteria for numbers

CriterionExamples of numbers
Even2, 4, 6, 8
Odd1, 3, 5, 7
Square numbers1, 4, 9, 16, 25
Prime numbers2, 3, 5, 7, 11, 13
1
Rule 1

See even and odd. Three even and one odd, or the opposite.

  • E.g. 2, 4, 7, 8. Of the four, 7 is odd. 7 is different.
2
Rule 2

See the table or multiples. Is each divisible by the same number?

  • E.g. 6, 12, 18, 25. The first three are divisible by 6. 25 is not. 25 is different.
3
Rule 3

Know the square numbers : 1, 4, 9, 16, 25, 36, 49, 64, 81.

  • E.g. 4, 9, 16, 20. The first three are square numbers. 20 is not a square number.
4
Rule 4

Know the prime numbers : numbers divisible only by 1 and themselves (2, 3, 5, 7, 11, 13, 17, 19, 23).

  • E.g. 3, 5, 7, 9. The first three are prime. 9 is divisible by 3. 9 is different.
Example 1 · easy

2, 4, 6, 9. Which is different?

  1. 2, 4, 6 are even. 9 is odd.
  2. Answer : 9.
Example 2 · medium

8, 16, 24, 30. Which is different?

  1. 8, 16, 24 are in the table of 8.
  2. 30 is not divisible by 8. Answer : 30.
Example 3 · exam type

11, 13, 15, 17. Which is different?

  1. 11, 13 and 17 are prime numbers.
  2. 15 is divisible by 3 and 5. Answer : 15.
Remember

Apply one criterion to all four numbers : it fits three and not one.

Common mistake

Taking 1 as a prime number. 1 is not prime; a prime number has two factors.

Shortcut

Memory clue : "Even-odd, table, square, prime : four criteria."

Shortcut

If the numbers are close together check the table first; if they are far apart, check squares or primes.

Spot the difference

SignWhich criterion
Some even, some oddEven-odd
Divisible by the same numberTable
Growing as 4, 9, 16Squares
Divisible only by 1 and itselfPrime

Practice questions

Easy
  1. 13, 5, 8, 11. Which is different?
  2. 210, 20, 30, 35. Which is different?
  3. 31, 4, 9, 12. Which is different?
Medium
  1. 414, 21, 28, 30. Which is different?
  2. 516, 25, 36, 48. Which is different?
  3. 67, 14, 21, 25. Which is different?
Challenging
  1. 727, 36, 45, 50. Which is different?
  2. 822, 33, 44, 55, 56. Which is different?
Show answers (try them yourself first)
  1. 18 (even; the others are odd).
  2. 235 (not in the table of 10).
  3. 312 (not a square number).
  4. 430 (not divisible by 7; the others are in the table of 7).
  5. 548 (not a square number; the others are 4², 5², 6²).
  6. 625 (not in the table of 7).
  7. 750 (27, 36, 45 are in the table of 9; 50 is not divisible by 9).
  8. 856 (all the others are in the table of 11; 56 is not divisible by 11).

The odd one out among letter groups

From daily life

In a letter game if "BCD" comes along with "ACE, GIK, MOQ", it looks different. In the first three groups we skip one letter each time, but BCD has letters one after the other.

Simple definition

In a group of letters give the letters numbers (A = 1, B = 2 …). Then look at the differences of the numbers in every group. The group with a different difference is the odd one out. Vowel-consonant and opposite letters can also be criteria.

Criteria for letter groups

CriterionExample
Same differenceACE (1, 3, 5), GIK (7, 9, 11)
All vowelsAE, IO
Opposite letter pairAZ, BY, CX
1
Rule 1

Find the differences of the letters in each group. The group that behaves differently is different.

  • E.g. ACE, GIK, MOQ, BCD. The first three have differences +2, +2. BCD has +1, +1. BCD is different.
2
Rule 2

Tell the vowels (A, E, I, O, U) and consonants apart.

  • E.g. AE, IO, UA, BC. In the first three both are vowels. BC are both consonants. BC is different.
3
Rule 3

See whether a pair is of opposite letters : the numbers add up to 27.

  • E.g. AZ, BY, CX, DV. A + Z = 27, B + Y = 27, C + X = 27. D + V = 4 + 22 = 26. DV is different.
4
Rule 4

Check both the difference inside a pair and the gap between the pairs.

  • E.g. AB, CD, EF, GI. In the first three the difference is 1. In GI the difference is 2. GI is different.
Example 1 · easy

AB, CD, EF, GJ. Which is different?

  1. AB, CD, EF have difference 1. GJ has difference 3.
  2. Answer : GJ.
Example 2 · medium

AZ, BY, CX, DV. Which is different?

  1. The first three pairs add up to 27. D + V = 26.
  2. Answer : DV.
Example 3 · exam type

KMO, QSU, BCE, EGI. Which is different?

  1. KMO : 11, 13, 15 (+2, +2). QSU : 17, 19, 21 (+2, +2). EGI : 5, 7, 9 (+2, +2).
  2. BCE : 2, 3, 5 (+1, +2). Answer : BCE.
Remember

Write the difference of each group next to it; the different difference shows at once.

Common mistake

Looking only at the difference of the first two letters. Check up to the third letter.

Shortcut

Memory clue : "Letter = number, then difference."

Shortcut

For groups of pairs check both : do they add up to 27 and is the difference the same?

Spot the difference

Sign of the groupHow to check
Three lettersFind two differences
Two lettersSee the difference and the sum
VowelsKnow A, E, I, O, U

Practice questions

Easy
  1. 1CAT, BAT, RAT, CUP. Which is different?
  2. 2AB, CD, EF, GJ. Which is different?
  3. 3AE, IO, UA, BC. Which is different?
Medium
  1. 4BD, FH, JL, MN. Which is different?
  2. 5EV, FU, GT, HR. Which is different?
  3. 6PQR, XYZ, DEF, LNO. Which is different?
Challenging
  1. 7AC, EG, IK, MP. Which is different?
  2. 8ABD, EFH, IJL, MNQ. Which is different?
Show answers (try them yourself first)
  1. 1CUP (the other three end in AT).
  2. 2GJ (difference 3; the others 1).
  3. 3BC (both consonants).
  4. 4MN (difference 1; the others 2).
  5. 5HR (H + R = 8 + 18 = 26; the others 27).
  6. 6LNO (L, N, O are not consecutive; the others are).
  7. 7MP (M + 3 = P, the others +2).
  8. 8MNQ (13, 14, 17 : +1, +3; the others +1, +2).

The odd one out among pairs

From daily life

Look at prices in a shop : 1 pen Rs 5, 2 pens Rs 10, 3 pens Rs 15. If 4 pens were written as Rs 22, that would be wrong. The two numbers of a pair have a fixed link.

Simple definition

In a group of pairs (e.g. (2, 4), (3, 6)) the second number of each pair has a rule with the first. Three pairs follow one rule and one pair is different. That one is the odd one out.

Rules for pairs

RuleExample
Double(2, 4), (3, 6), (5, 10)
Square(2, 4), (3, 9), (4, 16)
Add a fixed number(2, 5), (3, 6), (4, 7)
1
Rule 1

Find the rule from the first pair : double, triple, square, add.

  • E.g. (2, 4), (3, 6), (4, 8), (5, 11). The rule is double. Double of 5 is 10, but it is 11. (5, 11) is different.
2
Rule 2

Know the square rule : first number × first number.

  • E.g. (2, 4), (3, 9), (4, 16), (5, 20). 5 × 5 = 25, but it is 20. (5, 20) is different.
3
Rule 3

See whether the sum or the difference is fixed.

  • E.g. (3, 7), (4, 6), (5, 5), (6, 3). Sums 10, 10, 10, 9. (6, 3) is different.
4
Rule 4

In letter-number pairs find the number of the letter : (A, 1), (B, 2), (C, 3) …

  • E.g. (A, 1), (B, 2), (C, 3), (D, 5). D = 4. (D, 5) is different.
Example 1 · easy

(2, 4), (3, 6), (4, 8), (5, 11). Which pair is different?

  1. The rule is double. 5 × 2 = 10, not 11.
  2. Answer : (5, 11).
Example 2 · medium

(1, 1), (2, 4), (3, 9), (4, 12). Which pair is different?

  1. The rule is square. 4 × 4 = 16, not 12.
  2. Answer : (4, 12).
Example 3 · exam type

(5, 25), (6, 36), (7, 49), (8, 56). Which pair is different?

  1. The rule is square. 5², 6², 7² are right. 8² = 64, not 56.
  2. Answer : (8, 56).
Remember

The first two pairs are enough to find the rule. Check whether it fits the third and fourth.

Common mistake

Fixing the rule from one pair only. (2, 4) fits both double and square. Decide after seeing the next pair.

Shortcut

Memory clue : "Double, square, add, subtract : check four rules."

Shortcut

Once you know the rule, apply it to the first number and match the second; the one that does not match is different.

Spot the difference

SignRule
Second number is double the firstDouble
Second number is first × firstSquare
Second − first is fixedAdding

Practice questions

Easy
  1. 1(1, 2), (2, 4), (3, 6), (4, 9). Which pair is different?
  2. 2(2, 5), (3, 6), (4, 7), (5, 9). Which pair is different?
  3. 3(10, 5), (8, 4), (6, 3), (4, 1). Which pair is different?
Medium
  1. 4(2, 8), (3, 12), (4, 16), (5, 24). Which pair is different?
  2. 5(3, 9), (4, 16), (5, 25), (6, 30). Which pair is different?
  3. 6(1, 9), (2, 8), (3, 7), (4, 5). Which pair is different?
Challenging
  1. 7(A, 2), (B, 4), (C, 6), (D, 9). Which pair is different?
  2. 8(2, 6), (3, 12), (4, 20), (5, 30), (6, 43). Which pair is different?
Show answers (try them yourself first)
  1. 1(4, 9). The rule is double; 4 × 2 = 8.
  2. 2(5, 9). The rule is +3; 5 + 3 = 8.
  3. 3(4, 1). The rule is half; half of 4 is 2.
  4. 4(5, 24). The rule is × 4; 5 × 4 = 20.
  5. 5(6, 30). The rule is square; 6 × 6 = 36.
  6. 6(4, 5). The sums are 10, 10, 10, 9.
  7. 7(D, 9). The rule is double the letter; D = 4, double is 8.
  8. 8(6, 43). The rule is first × next; 2 × 3 = 6, 3 × 4 = 12, 4 × 5 = 20, 5 × 6 = 30. 6 × 7 = 42, not 43.

Mixed questions and exam tricks

From daily life

Sometimes more than one criterion shows up and we get confused. In 4, 9, 16, 21 which number is different? If we look at even-odd we get two and two, so that criterion does not work. With squares the answer is found.

Simple definition

The criterion that separates one is the true criterion. If you get two and two, try another criterion. After getting the answer look again to see whether the other three really are alike.

List of all criteria

GroupCriteria
WordsClass, use, place
NumbersEven-odd, table, square, prime
LettersDifference, vowels, opposite letters
PairsDouble, square, sum
1
Rule 1

From the list of criteria apply one by one to all four choices.

  • E.g. 3, 5, 7, 8. Even-odd : 8 is even, the others odd. 8 is different.
2
Rule 2

You need a split of three and one. If it is two and two, it is not the criterion.

  • E.g. 4, 9, 16, 21. Even-odd : 4, 16 even; 9, 21 odd (two and two). That criterion does not work.
3
Rule 3

Change the criterion and use a new one.

  • E.g. 4, 9, 16, 21 with squares : 4, 9, 16 are squares; 21 is not. 21 is different.
4
Rule 4

Check the answer : do the other three really share the same criterion?

  • E.g. Are 4, 9, 16 squares? 2², 3², 4². Yes.
Example 1 · easy

12, 18, 24, 29. Which is different?

  1. 12, 18, 24 are in the table of 6.
  2. 29 is not divisible by 6. Answer : 29.
Example 2 · medium

Rose, jasmine, mango, marigold. Which is different?

  1. Rose, jasmine and marigold are flowers.
  2. Mango is a fruit. Answer : Mango.
Example 3 · exam type

4, 9, 16, 21. Which is different?

  1. Even-odd : two and two, it does not work.
  2. Squares : 4 = 2², 9 = 3², 16 = 4². 21 is not a square. Answer : 21.
Remember

If you get two and two, try another criterion.

Common mistake

Giving an answer from a wrong first criterion. If the answer is not checked, mistakes happen.

Shortcut

Memory clue : "Three and one; if two and two, change the criterion."

Shortcut

After getting the answer, ask once, "Are the other three really alike?"

Spot the difference

SplitMeaning
Three and oneThe criterion is right
Two and twoChange the criterion
All four alikeLook for another criterion

Practice questions

Easy
  1. 12, 4, 6, 7. Which is different?
  2. 2Spoon, plate, bowl, stone. Which is different?
  3. 3AB, BC, CD, CE. Which is different?
Medium
  1. 46, 12, 18, 20. Which is different?
  2. 5Red, green, yellow, peacock. Which is different?
  3. 65, 10, 15, 22. Which is different?
Challenging
  1. 71, 4, 9, 16, 24. Which is different?
  2. 817, 19, 23, 27, 29. Which is different?
Show answers (try them yourself first)
  1. 17 (odd; the others are even).
  2. 2Stone (the others are dining utensils).
  3. 3CE (difference 2; the others difference 1).
  4. 420 (not in the table of 6).
  5. 5Peacock (not a colour; the others are colours).
  6. 622 (not in the table of 5).
  7. 724 (not a square number; the others are 1², 2², 3², 4²).
  8. 827 (not a prime number; 27 is divisible by 3; the others are prime).

Quick revision of the whole lesson

TypeMemory clue
WordsHow are the three alike? The one that is not, is odd
NumbersEven-odd, table, square, prime
Letter groupsLetter = number, then difference
PairsDouble, square, add, subtract
MixedThree and one; if two and two, change the criterion
CheckingAre the other three really alike?

🎯 Most important points for the exam

  • First find the criterion that joins three of them; the one that does not fit is different.
  • For words look at class, use and place.
  • For numbers check even-odd, table, square and prime.
  • For letter groups give numbers and find the differences; for pairs see whether the sum is 27.
  • For pairs check the rules double, square, sum and difference.
  • You need a split of three and one; if it is two and two, change the criterion.
  • After getting the answer check whether the other three are really alike.
🧠 Study mantra

"Find the criterion, pick the one that does not fit; check at the end."