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

Directions: In the following series, one of the terms given is wrong. Find the incorrect term and mark that as your answer. 218 154 105 68 44 28 19

  1. 68

  2. 19

  3. 154

  4. 105

  5. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The differences are: 218-154=64, 154-105=49, 105-68=37, 68-44=24, 44-28=16, 28-19=9. The pattern of differences should be squares (8^2, 7^2, 6^2, 5^2, 4^2, 3^2). 105-68 should be 36, so 105-36 = 69. If 69 were there, 69-44=25 (5^2). Thus 68 is the incorrect term.

Multiple choice

Directions: In the following series, one of the given terms is wrong. Find that term and mark that as your answer. 323, 221, 143, 79, 35, 15

  1. 79

  2. 143

  3. 323

  4. 221

  5. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The sequence is 323, 221, 143, 79, 35, 15. Differences: 102, 78, 64, 44, 20. This doesn't look like a simple pattern. Let's check prime factors: 323=17*19, 221=13*17, 143=11*13, 91=7*11, 55=5*7, 35=5*7. The pattern is products of consecutive primes: 17*19, 13*17, 11*13, 7*11, 5*7, 3*5. The term 79 is wrong; it should be 7*11 = 77.