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Number and letter series
10 MDCAT Logical reasoning questions with answers and explanations.
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Find the next number: 2, 4, 8, 16, ?
- 1 24
- 2 32
- 3 30
- 4 64
Show answer
Correct answer: 32
Each number is double the one before it, so the next is 16 x 2 = 32.
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Find the next number: 3, 6, 11, 18, 27, ?
- 1 36
- 2 38
- 3 40
- 4 45
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Correct answer: 38
The differences are 3, 5, 7 and 9, which go up by 2 each time. The next difference is 11, so 27 + 11 = 38.
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Find the next number: 1, 4, 9, 16, 25, ?
- 1 30
- 2 49
- 3 36
- 4 34
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Correct answer: 36
These are the squares of 1, 2, 3, 4 and 5, so the next is 6 squared, which is 36.
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Find the next number: 100, 93, 86, 79, ?
- 1 72
- 2 71
- 3 73
- 4 69
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Correct answer: 72
Each number is 7 less than the one before it, so the next is 79 - 7 = 72.
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Find the next number: 2, 3, 5, 7, 11, 13, ?
- 1 15
- 2 17
- 3 19
- 4 21
Show answer
Correct answer: 17
These are the prime numbers in order. The next prime after 13 is 17.
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Find the next letter: A, C, E, G, ?
- 1 H
- 2 J
- 3 I
- 4 K
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Correct answer: I
The letters skip one each time, so after G (skipping H) comes I.
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Find the next letter: Z, X, V, T, ?
- 1 S
- 2 Q
- 3 R
- 4 P
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Correct answer: R
The letters move back two places each time. After T (skipping S) comes R.
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Find the next number: 1, 1, 2, 3, 5, 8, ?
- 1 11
- 2 12
- 3 13
- 4 15
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Correct answer: 13
Each number is the sum of the two before it, so the next is 5 + 8 = 13.
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Find the next pair: AZ, BY, CX, DW, ?
- 1 EV
- 2 EU
- 3 FV
- 4 EX
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Correct answer: EV
The first letter moves forward one place and the second moves back one place each time, so the next pair is EV.
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Find the next number: 5, 10, 20, 40, ?
- 1 60
- 2 70
- 3 80
- 4 100
Show answer
Correct answer: 80
Each number is double the one before it, so the next is 80.