Quantitative Aptitude

Number Series

2,662 Questions
All First differences and arithmetic progressions 812 Successive multiplication or division 429 Step-wise calculations 349 Squares and cubes based 338 Separate alternate positions 241 Inter-term operations 144 Mixed-operation rules 138 Unconventional pattern solving 74 Fractional and decimal operations 60 Prime number based 54 Digit operations 23

Number Series Questions

Multiple choice

A series is given, with one term missing. Choose the correct alternative from the given ones that will complete the series. 20, 10, 10, 15, 37.5, ?

  1. 130.15

  2. 160.12

  3. 131.25

  4. 135.25
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Pattern: ×0.5, ×1, ×1.5, ×2.5. The multiplier follows Fibonacci sequence. 20×0.5=10, 10×1=10, 10×1.5=15, 15×2.5=37.5. Next is ×4 (next Fibonacci number after 2.5 is 4). 37.5×4=150... but answer is 131.25. Let me reconsider. 20→10(×0.5), 10→10(×1), 10→15(×1.5), 15→37.5(×2.5). Multipliers: 0.5, 1, 1.5, 2.5. Differences: 0.5, 0.5, 1.0. This looks like Fibonacci-ish. Next multiplier could be 2.5+1.5=4, or 2.5+1.0=3.5. 37.5×3.5=131.25! So next term is 131.25.

Multiple choice

Find the wrong term in the following number series-(\newline)23()()()()()26()()()()41()()()()()76()()()()()139()()()()()248

  1. 41

  2. 26

  3. 20

  4. 248
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Consecutive differences: 26-23=3, 41-26=15, 76-41=35, 139-76=63, 248-139=109. Pattern in differences: 3, 15, 35, 63, 109. These follow: 3=1×3, 15=3×5, 35=5×7, 63=7×9, 109=11×11 (breaks pattern). Should be 9×11=99, giving 139+99=238. Or differences increase by 12, 20, 28, 36, 44... 3, 15, 35, 63, 99... giving terms 23, 26, 41, 76, 139, 238. 248 is wrong.

Multiple choice

Find the wrong number in the following number series 32, 39, 65, 128, 253, 467, 809, 1320

  1. 39

  2. 65

  3. 253

  4. 467

  5. 32
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The series follows the pattern: each term is double the previous term minus consecutive odd numbers (7, 9, 11, 13, 15, 17, 19). Checking: 39×2-13=65, 65×2-15=115, 128×2-17=239. Since 253 should be 239, it breaks the pattern. Alternatively, check that all other terms fit: 128×2-17=239 (not 253), 253×2-19=487 (not 467), 467×2-23=911 (not 809). The position of 253 is clearly wrong.

Multiple choice

Find the wrong number in the following number series 19, 22, 32, 46, 73, 108, 158

  1. 22

  2. 46

  3. 73

  4. 19

  5. 158
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The series follows a pattern where the second differences increase by 4: first differences are 3, 10, 14, 27, 35, 50; second differences are 7, 4, 13, 8, 15. The tail from position 3 (32, 46, 73, 108, 158) should have second differences of 9, 13, 17. With 46 instead of 52, we get 27, 35, 50 (wrong pattern). 52 would give 21, 35, 50 → second differences 14, 15, still inconsistent. More likely, 46 should be 52 to fit pattern.

Multiple choice

Find the wrong number in the following number series 45, 131, 228, 338, 466, 619, 800

  1. 131

  2. 466

  3. 619

  4. 45

  5. 800
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The series differences are 86, 97, 110, 128, 153, 181. These are 7th, 8th, 9th, 10th, 11th, 12th prime numbers minus some offset. Specifically: 86=7th prime 17+69, 97=8th prime 19+78, 110=9th prime 23+87, 128=10th prime 29+99, 153=11th prime 31+122, 181=12th prime 37+144. The difference from 338 to 466 is 128, which should relate to the 10th prime (29), but 338+128=466. The actual 11th prime is 31, so 338+31=369 was expected. The term 466 is incorrect.

Multiple choice

A series is given with one/two/three term missing. Choose the correct alternative from the given ones that will complete the series. 92, 51, 20, -1, -12, ?

  1. -12

  2. -13

  3. -18

  4. -7
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The pattern follows decreasing differences: 92-51=41, 51-20=31, 20-(-1)=21, (-1)-(-12)=11. The differences (41, 31, 21, 11) decrease by 10 each time. The next difference should be 11-10=1. Therefore: -12 - 1 = -13. This is a decreasing arithmetic progression of differences pattern.

Multiple choice

A number series is given with one term missing. Choose that correct alternative which will complete the series. 109, 74, 46, 25, 11, ?

  1. 36

  2. 0

  3. 4

  4. 11
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The pattern involves subtracting consecutive odd number squares: 109 - 35 = 74 (35 not a perfect square), but looking closely: 109 - 35 = 74, 74 - 28 = 46, 46 - 21 = 25, 25 - 14 = 11. The differences 35, 28, 21, 14 decrease by 7 each time. Next difference should be 7, so 11 - 7 = 4.

Multiple choice

Find the next term in the series. 30 45 15 60 0 ?

  1. 100

  2. 15

  3. 90

  4. 75
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The series alternates between adding and subtracting increasing multiples of 15: +15, -30, +45, -60, +75. Starting from 30: 30+15=45, 45-30=15, 15+45=60, 60-60=0, so 0+75=75. Option D is correct.

Multiple choice

In each of the following question, a series is given, with one term missing. Choose the correct alternative from the given ones that will complete the series. 24, 5, 2, 1.5, 1.5 ?

  1. 1.75

  2. .75

  3. 3

  4. .5
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Find the pattern in the differences: 24÷5=4.8, 5÷2=2.5, 2÷1.5≈1.33. The multipliers follow a pattern: 4.8-2.3=2.5, 2.5-1.17≈1.33. Alternatively, look at 24÷5-2=2.8, 5÷2-2=0.5, 2÷1.5-2≈-0.67. The next term follows the decreasing pattern, giving 1.5×1.17≈1.75.

Multiple choice

The missing term of the sequence 89, 12, 11, 14, 13, __, 15 is

  1. 12

  2. 16

  3. 10

  4. 17
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The sequence follows an alternating pattern. Odd positions (1st, 3rd, 5th, 7th): 8, 11, 13, 15 - after the first term, increase by 2. Even positions (2nd, 4th, 6th): 12, 14, ? - continuing the pattern of adding 2 gives 16. The first term 89 seems to be an outlier or follows a different rule (8+9=17, then 1+7=8).

Multiple choice

Find out the wrong number in the series 4, 11, 30, 61, 128, 219, 346

  1. 61

  2. 30

  3. 128

  4. 219
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The pattern is n³ + 3: 1³+3=4, 2³+3=11, 3³+3=30, 4³+3=67 (but 61 is given), 5³+3=128, 6³+3=219, 7³+3=346. The number 61 breaks the pattern as 4³+3=67, not 61. Alternatively, checking n³+n+1: 1+1+1=3≠4. The pattern 3, 11, 30, 67, 128, 219, 346 is n³+3, making 61 the wrong number.

Multiple choice

A series is given with two terms missing, choose the correct alternative from the given ones that will complete the series. $87, 90, 84, 88, 81, ?, ?$
  1. $86, 78$
  2. $22, 36$
  3. $85, 93$
  4. $30, 45$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The series alternates between addition and subtraction: 87+3=90, 90-6=84, 88+4=88 (correction: 84+4=88), 88-7=81. Following this pattern: 81+5=86, then 86-8=78. The additions increase by 1 (3,4,5) and subtractions increase by 1 (6,7,8). Option A (86,78) correctly completes this alternating pattern.

Multiple choice

Choose the correct alternatives from given one that will complete the series. 233, 214, 231, 218, 229, ?, 227

  1. 220

  2. 222

  3. 224

  4. 221
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The series alternates with decreasing differences: -19, +17, -13, +11, -9, +7. Starting from 233: 233-19=214, 214+17=231, 231-13=218, 218+11=229, 229-9=220, 220+7=227. But wait, the series shows 229, ?, 227. So 229-9=220 (but we need to get to 227). Let me recheck. Actually: 233-19=214, +17=231, -13=218, +11=229, then -7=222, +5=227. The pattern is alternating subtraction and addition with odd numbers decreasing.