ISSB - PAF Officer Selection intelligence: Number Series MCQs

Practice Number Series MCQs for ISSB - PAF Officer Selection intelligence — topic-wise sets with solved answers.

ISSB - PAF Officer Selection intelligence: Number Series MCQs — sample questions

  1. Question 1

    Q1. Which number replaces ?: 3, 9, 27, ?, 243

    • A) 54
    • B) 72
    • C) 81
    • D) 90

    Answer: 81

    Explanation: Geometric series ×3 each step: 27×3 = 81. Check 81×3 = 243 confirms. Always verify with the next term.

  2. Question 2

    Q2. Complete: 81, 27, 9, 3, ?

    • A) 0
    • B) 1
    • C) 2
    • D) 6

    Answer: 1

    Explanation: Divide by 3 each step. After 3 comes 1. Work each step carefully; ISSB math rewards accuracy under time pressure.

  3. Question 3

    Q3. Complete: 2, 6, 12, 20, 30, ?

    • A) 40
    • B) 42
    • C) 44
    • D) 50

    Answer: 42

    Explanation: Differences +4, +6, +8, +10, next +12 gives 42. Pattern n(n+1). Work each step carefully; ISSB math rewards accuracy under time pressure.

  4. Question 4

    Q4. Which number replaces ?: 5, 10, 20, 40, ?

    • A) 60
    • B) 70
    • C) 80
    • D) 100

    Answer: 80

    Explanation: Each term doubles. 40 x 2 = 80. Work each step carefully; ISSB math rewards accuracy under time pressure.

  5. Question 5

    Q5. Find the missing number: 2, 6, 12, 20, 30, ?

    • A) 40
    • B) 38
    • C) 44
    • D) 42

    Answer: 42

    Explanation: The gaps between terms grow by 2 each time (4, 6, 8, 10). The next gap is 12, so 30 plus 12 equals 42.

  6. Question 6

    Q6. What number comes next when each term is halved: 64, 32, 16, 8, ?

    • A) 4
    • B) 2
    • C) 6
    • D) 0

    Answer: 4

    Explanation: Each number is half of the previous term. Half of 8 is 4.

  7. Question 7

    Q7. Find the next number: 3, 9, 27, 81, ?

    • A) 162
    • B) 243
    • C) 324
    • D) 729

    Answer: 243

    Explanation: Each term is multiplied by 3. Eighty-one times 3 equals 243. Work each step carefully; ISSB math rewards accuracy under time pressure.

  8. Question 8

    Q8. Find the missing number: 7, 14, 28, 56, ?, 224.

    • A) 84
    • B) 98
    • C) 112
    • D) 168

    Answer: 112

    Explanation: Each term is double the previous one. Fifty-six times 2 is 112, and 112 times 2 is 224.

  9. Question 9

    Q9. Find the next number: 1, 4, 9, 16, 25, ?

    • A) 30
    • B) 36
    • C) 49
    • D) 64

    Answer: 36

    Explanation: These are squares of 1, 2, 3, 4, and 5. The next is 6 squared, which is 36.

  10. Question 10

    Q10. Find the next number: 2, 3, 5, 8, 12, ?

    • A) 16
    • B) 17
    • C) 18
    • D) 20

    Answer: 17

    Explanation: Differences are 1, 2, 3, 4, so the next difference is 5. 12 plus 5 equals 17.

  11. Question 11

    Q11. Next number: 2, 4, 8, 16, ?

    • A) 24
    • B) 30
    • C) 32
    • D) 36

    Answer: 32

    Explanation: Each term doubles. 16 times 2 equals 32. Work each step carefully; ISSB math rewards accuracy under time pressure.

  12. Question 12

    Q12. Next number: 7, 14, 21, 28, ?

    • A) 32
    • B) 35
    • C) 36
    • D) 42

    Answer: 35

    Explanation: The series increases by 7. 28 plus 7 equals 35. Work each step carefully; ISSB math rewards accuracy under time pressure.

  13. Question 13

    Q13. Next number: 3, 6, 9, 12, ?

    • A) 14
    • B) 15
    • C) 16
    • D) 18

    Answer: 15

    Explanation: The series increases by 3. 12 plus 3 equals 15. Work each step carefully; ISSB math rewards accuracy under time pressure.

  14. Question 14

    Q14. Next number: 10, 9, 7, 4, ?

    • A) 0
    • B) 1
    • C) 2
    • D) 3

    Answer: 0

    Explanation: Differences are -1, -2, -3, so next is -4. 4 minus 4 equals 0.

  15. Question 15

    Q15. Next: 4, 9, 16, 25, ?

    • A) 30
    • B) 36
    • C) 49
    • D) 64

    Answer: 36

    Explanation: These are squares of 2, 3, 4, and 5. Next is 6 squared, which is 36.

  16. Question 16

    Q16. Next: 5, 10, 20, 40, ?

    • A) 60
    • B) 80
    • C) 70
    • D) 90

    Answer: 80

    Explanation: Each term doubles. 40 times 2 equals 80. Work each step carefully; ISSB math rewards accuracy under time pressure.

  17. Question 17

    Q17. Next: 2, 3, 5, 8, 12, ?

    • A) 16
    • B) 17
    • C) 18
    • D) 20

    Answer: 17

    Explanation: Differences are 1, 2, 3, 4, so next is 5. 12 plus 5 equals 17.

  18. Question 18

    Q18. Next: 100, 96, 91, 85, ?

    • A) 78
    • B) 80
    • C) 77
    • D) 76

    Answer: 78

    Explanation: Differences are -4, -5, -6, so next is -7. 85 minus 7 equals 78.

  19. Question 19

    Q19. Next: 1, 2, 4, 8, 16, ?

    • A) 24
    • B) 32
    • C) 30
    • D) 20

    Answer: 32

    Explanation: Each term doubles. 16 times 2 equals 32. Work each step carefully; ISSB math rewards accuracy under time pressure.

  20. Question 20

    Q20. Next: 11, 13, 17, 19, 23, ?

    • A) 25
    • B) 29
    • C) 27
    • D) 31

    Answer: 29

    Explanation: These are prime numbers. Next prime after 23 is 29. Work each step carefully; ISSB math rewards accuracy under time pressure.

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