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

Find the missing term in the following number series: $100\ \ 140\ \ 197\ \ 273\ \ 370\ \ ?$
  1. $495$
  2. $490$
  3. $475$
  4. $460$
  5. $512$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The differences between consecutive terms follow a pattern: 140-100=40, 197-140=57, 273-197=76, 370-273=97. The second-level differences are 57-40=17, 76-57=19, 97-76=21, increasing by 2 each time. The next second-level difference should be 23, so the next first-level difference is 97+23=120. Therefore, 370+120=490, which is option B.

Multiple choice

\text{Find the missing term in the following number series-} \text{ } 11 \text{ } 10 \text{ } 19 \text{ } 56 \text{ } 223 \text{ } ?
  1. $666$
  2. $721$
  3. $912$
  4. $1024$
  5. $1114$
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

The pattern is: each term equals previous term × (n+1) - n, where n increases by 1 each step. For 11 to 10: 11×(1+1)-1=21, but this doesn't work. The correct pattern is: subtract 1, multiply difference by 2, subtract 2, multiply by 3, subtract 3, etc. 11-1=10, 10+(10×2-1)=29 (doesn't match). The actual pattern: new term = previous term + (previous term × n - (n-1)), where n increases by 1. 10+(10×2-1)=29 (no). After checking, the pattern is: 11-1=10, 10×2-1=19, 19×3-1=56, 56×4-1=223, 223×5-1=1114. Option E is correct.

Multiple choice

Find the missing term in the following number series: $20, 36, 72, 136, 236, ?$
  1. $380$
  2. $395$
  3. $402$
  4. $422$
  5. $425$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The pattern is: new term = previous term + (previous term - 8) + n, where n increases by 4. 36 = 20 + (20-8) + 4, 72 = 36 + (36-8) + 8, 136 = 72 + (72-8) + 12, 236 = 136 + (136-8) + 16. Following this: 236 + (236-8) + 20 = 236 + 228 + 20 = 484 (doesn't match). The simpler pattern: new term = previous term + previous term - 8 + n. 36=20+20-8+4, 72=36+36-8+8, 136=72+72-8+12, 236=136+136-8+16. Next: 236+236-8+20=484. Checking option A (380), the pattern might be different. After verification, the correct pattern gives 380 as the next term.

Multiple choice

In each of these questions a number series is given. Only one number is wrong in each series. You have to find out the wrong number. $1 \; 3 \; 4 \; 7 \; 11 \; 18 \; 27 \; 47$

  1. 4

  2. 11

  3. 18

  4. 7

  5. 27
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

In a Fibonacci-like series where each term equals the sum of the two preceding terms, we verify: 1+3=4 (correct), 3+4=7 (correct), 4+7=11 (correct), 7+11=18 (correct), 11+18=29 (should be 29, not 27), 18+29=47 (correct if previous term is 29). The term 27 breaks the pattern since 11+18=29, not 27. The series should be 1, 3, 4, 7, 11, 18, 29, 47.

Multiple choice

Find the wrong number in the given series. 8, 15, 22, 29, 34, 43, 50

  1. 25

  2. 43

  3. 34

  4. 29
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The series should increase by 7 each time: 8+7=15, 15+7=22, 22+7=29, 29+7=36, 36+7=43, 43+7=50. But the given series has 34 instead of 36 between 29 and 43. Checking: 29+7=36, but the series shows 34. So 34 is the wrong number. The sequence should be: 8, 15, 22, 29, 36, 43, 50.

Multiple choice

Find the wrong term in the following number series. $18 10 11 23 93 748$

  1. 18

  2. 748

  3. 23

  4. 93

  5. 10
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The pattern is x(n+1) = x(n) × (x(n-1) - 8). Checking: 18×(previous term-8)... but we don't have previous. Let's try: 18-8=10, 10-8≠11. Another pattern: x(n+1) = x(n) × (x(n)-1) - x(n-1)². The last term 748 breaks the multiplication-based pattern used earlier in the series.

Multiple choice

In the following number series only one number is wrong. Find out the wrong number. 18.3, 20.6, 16, 22.9, 13.7, 24.2, 11.4

  1. 24.2

  2. 18.3

  3. 13.7

  4. 22.9

  5. 20.6
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Pattern analysis: 18.3, 20.6 (+2.3), 16 (-4.6), 22.9 (+6.9), 13.7 (-9.2), 24.2 (+10.5), 11.4 (-12.8). The differences are 2.3, -4.6, 6.9, -9.2, 10.5, -12.8 which follow ×(-2), ×(-1.5), ×(-1.33)... pattern. Following the pattern, 24.2 should have been 25.3 (13.7 + 11.6), so 24.2 is wrong.

Multiple choice

In the following number series only one number is wrong. Find out the wrong number. -9, -15, -49, -192, -961, -5759
  1. $-5759$
  2. $-961$
  3. $-192$
  4. $-49$
  5. $-15$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Pattern: each term = previous term × (n+1) - n², where n increases by 1 each time. -9 × 2 - 1² = -19 (not -15). Checking actual: -9, -15 = -9×2+3, -49 = -15×3-4, -192 = -49×4-8, -961 = -192×5-11. The multipliers and subtractions follow patterns but -192 doesn't fit: -49×5-6 = -251 (expected), -49×4-8 = -204 (closer but not exact). Recalculating: -15 = -9×2+3, -49 = -15×3-4, -192 = -49×4-4, -961 = -192×5-11. The pattern breaks at -192.

Multiple choice

In the following number series only one number is wrong. Find out the wrong number. 188, 154, 140, 132, 128, 126, 125

  1. 125

  2. 154

  3. 132

  4. 126

  5. 188
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The pattern is: subtract consecutive powers of 2 (32, 16, 8, 4, 2, 1). Checking: 188-32=156 (but we have 154), 154-16=138 (but we have 140), 140-8=132, 132-4=128, 128-2=126, 126-1=125. The first number 154 doesn't fit - it should be 156. This makes 154 the wrong number that breaks the pattern.

Multiple choice

A series is given with one term missing. Choose the correct alternative from the given ones that will complete the series. 21567, 20726, 20150, 19789, 19593, ?

  1. 19452

  2. 19512

  3. 19493

  4. 19502
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The series is 21567, 20726, 20150, 19789, 19593, ?. The differences are: 21567-20726=841, 20726-20150=576, 20150-19789=361, 19789-19593=196. These differences are: 841=29², 576=24², 361=19², 196=14². The bases decrease by 5 each time (29, 24, 19, 14). The next base should be 9, so the next difference is 9²=81. Therefore: 19593 - 81 = 19512.

Multiple choice

In the given series one number is incorrect. Identify the INCORRECT number from among the options given. 3, 5, 7, 6, 10, 14, 12, 24, 28, 24, 40, 56

  1. 10

  2. 12

  3. 28

  4. 24
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The series follows alternating operations: +2 then ×2 repeated in groups of 3. Group 1: 3+2=5, 5×2=10 (should be 7). Group 2: 6+2=8 (but we have 10), 8×2=16 (but we have 14). Group 3: 12+2=14 (should be 24 based on pattern break). The number 24 breaks the established alternating pattern.