Number Series Questions

Multiple choice general knowledge math & puzzles
  1. -7 , -17 , -27

  2. -25 , -26 , -27

  3. 27 , 0 , -27

  4. -21 , -24 , -27

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Using the arithmetic series formulas: nth term aₙ = a₁ + (n-1)d and sum Sₙ = n(a₁ + aₙ)/2. Given a₃ = 114, aₙ = -27, and S = 2325. From a₃ = a₁ + 2d = 114, we get a₁ = 114 - 2d. From S = n(a₁ + aₙ)/2 = n((114-2d) + (-27))/2 = n(87 - 2d)/2 = 2325. From aₙ = a₁ + (n-1)d: -27 = (114-2d) + (n-1)d = 114 - 2d + nd - d = 114 + nd - 3d. Solving gives d = -3, n = 60, a₁ = 120. The last three terms are: 58th = a₁ + 57d = 120 + 57(-3) = -51, 59th = 120 + 58(-3) = -54, 60th = 120 + 59(-3) = -57. Wait - this doesn't match option D. Let me recalculate: -27 = a₁ + (n-1)(-3), so a₁ = -27 + 3(n-1). Also a₁ = 114 - 2(-3) = 120. So 120 = -27 + 3n - 3, so 3n = 150, n = 50. Last three: 48th = 120 + 47(-3) = -21, 49th = 120 + 48(-3) = -24, 50th = 120 + 49(-3) = -27. This matches option D.

Multiple choice general knowledge math & puzzles
  1. 2700

  2. 2332

  3. 3456

  4. 3600

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

To solve this question, the user needs to identify the pattern in the given series of numbers.

The first number is 9, and each subsequent number is obtained by multiplying the previous number by a multiple of 2.

9 x 2 = 18 18 x 4 = 72 72 x 6 = 432 432 x 8 = 3456

Therefore, the missing number in the series is obtained by multiplying 432 by 8, which equals 3456.

So, the Answer is: C. 3456

Multiple choice general knowledge math & puzzles
  1. 74

  2. 45

  3. 11

  4. 109

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The series follows the pattern n^2 + n: 4=2^2+2, 11=3^2+2, 25=5^2+0 (doesn't fit), 45=6^2+9=45, 74=8^2+10=74, 109=10^2+9=109. The differences are: 11-4=7, 25-11=14, 45-25=20, 74-45=29, 109-74=35. Second differences: 14-7=7, 20-14=6, 29-20=9, 35-29=6. The inconsistent second differences around 25 and 45 suggest 45 or 25 is wrong. The answer key says 45 is wrong.

Multiple choice general knowledge math & puzzles
  1. 634

  2. 611

  3. 605

  4. 600

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The pattern alternates between adding and subtracting 23. Starting with 582: 582+23=605, 605-23=582 (not 588), 582+23=605, 605+23=628 (not 611). The correct pattern should be: 582, 605, 582, 605, 628, 651, 674 or similar. The number 634 appears where 628 should be if adding 23 consistently.

Multiple choice general knowledge math & puzzles
  1. 480

  2. 92

  3. 24

  4. 8

  5. 4

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

92 is the wrong number. The pattern is: divide by 6 and add 12 repeatedly. 2880/6+12=480, 480/6+12=92, but 92/6+12=27.33 (not 24). The pattern requires 92 to be 80 (80/6+12=25.33, still not 24). The correct pattern seems to be: divide by 6, 5, 4, 3, 2 respectively: 2880/6+12=492 (not 480). The number 92 breaks whatever pattern is intended.

Multiple choice general knowledge math & puzzles
  1. 78

  2. 19

  3. 20

  4. 22

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

First sequence: 17,21,25,... (difference 4). Terms = 17 + 4(n-1) for n=1 to 100. Second sequence: 16,21,26,... (difference 5). Terms = 16 + 5(n-1) for n=1 to 91. Common terms satisfy 17 + 4a = 16 + 5b → 4a - 5b = -1. Solving: terms are 21,41,61,...,401 (21 + 20k for k=0 to 19). Total = 20 terms.