Find the one which does not belong to that group ?
Answer: C
Lungs, eyes and ears each come as a pair - exactly two of each in the body.
Fingers come in fives on each hand, ten in all.
So Fingers does not belong.
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Find out the wrong number in the given sequence of numbers 25, 36, 49, 81, 121, 169, 225
Answer: A
The series is the squares of the odd numbers.
\[ 5^{2},\; 7^{2},\; 9^{2},\; 11^{2},\; 13^{2},\; 15^{2} = 25,\; 49,\; 81,\; 121,\; 169,\; 225 \]
\[ 36 = 6^{2}, \text{ the square of an even number} \]
So 36 is the wrong number. Being a perfect square, it fits the looser pattern - which is exactly the trap.
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Find out the wrong number in the given sequence of numbers 6, 13, 18, 25, 30, 37, 40
Answer: D
The differences alternate between \( +7 \) and \( +5 \).
\[ 6 \xrightarrow{+7} 13 \xrightarrow{+5} 18 \xrightarrow{+7} 25 \xrightarrow{+5} 30 \xrightarrow{+7} 37 \xrightarrow{+5} 42 \]
The last term should be \( 37 + 5 = 42 \), not 40.
So 40 is the wrong number.
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Find the odd man out. 3, 5, 11, 14, 17, 21
Answer: C
Every number in the list is odd except one.
\[ 3,\; 5,\; 11,\; 17,\; 21 \;\text{are odd}; \qquad 14 \;\text{is even} \]
So 14 is the odd man out. The list is deliberately salted with 21, which is not prime, to tempt the "all primes" reading - but 21 is still odd.
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Find the one which does not belong to that group ?
Answer: D
A trapezium, a square and a triangle are plane figures, drawn in two dimensions and measured by area.
A cube is a solid, occupying three dimensions and measured by volume.
So Cube does not belong.
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Insert the missing number 7, 26, 63, 124, 215, 342, (....)
Answer: B
Each term is one less than a perfect cube.
\[ 2^{3}-1 = 7,\quad 3^{3}-1 = 26,\quad 4^{3}-1 = 63,\quad 5^{3}-1 = 124 \]
\[ 6^{3}-1 = 215,\quad 7^{3}-1 = 342,\quad 8^{3}-1 = \mathbf{511} \]
The near miss 513 would be \( 8^{3} + 1 \) - the same cube with the sign of the correction flipped.
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Find out the wrong number in the given sequence of numbers 5, 16, 6, 16, 7, 16, 9
Answer: A
Two series are interleaved. The even positions are all 16, while the odd positions count up by one.
\[ \text{odd positions: } 5,\; 6,\; 7,\; \mathbf{8} \]
\[ \text{even positions: } 16,\; 16,\; 16 \]
The seventh term should be 8, not 9.
So 9 is the wrong number. The repeated 16 is the clue that two separate sequences are woven together.
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Find the one which does not belong to that group ?
Answer: D
Each number is a digit written next to its own square:
To follow the rule the last would have to be 416, so 426 is the one that does not belong.
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Insert the missing number 5, 10, 13, 26, 29, 58, 61, (....)
Answer: A
The operations alternate between doubling and adding 3.
\[ 5 \times 2 = 10,\quad 10 + 3 = 13,\quad 13 \times 2 = 26,\quad 26 + 3 = 29 \]
\[ 29 \times 2 = 58,\quad 58 + 3 = 61,\quad 61 \times 2 = \mathbf{122} \]
The next operation is a doubling because the previous one was an addition; 64 would come from adding 3 again.
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Find out the wrong number in the given sequence of numbers 105, 85, 60, 30, 0, -45, -90
Answer: D
The gaps should widen by 5 each time.
\[ 105 \xrightarrow{-20} 85 \xrightarrow{-25} 60 \xrightarrow{-30} 30 \xrightarrow{-35} -5 \xrightarrow{-40} -45 \xrightarrow{-45} -90 \]
The fifth term should be \( 30 - 35 = -5 \), not 0.
So 0 is the wrong number. Every term after it fits the corrected value, which confirms the single break.
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