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Tips to Solve Number series in SSC CGL Quantitative Aptitude

Last Updated - June 29, 2017

Number Series in SSC CGL can be one of the easiest scoring questions if one knows all the tricks and formulae. Every year almost 1-2 questions are asked from concepts related to Number Series. Candidates appearing in SSC CGL must follow the rules and preparation tips thoroughly to save time and score more at the time of examination. Identifying the logic behind the sequence can be tough and only practice will ease things out.

One of the tough aspects or challenge faced by candidates is that they tend to spend undue time in trying to solve these questions thereby having less time to focus on other questions.

With regular practice and guidance from recommended books and websites, candidates can greatly improve their performance in SSC CGL examination.

Number Series Weightage in SSC CGL

Questions based on completing the pattern, finding the missing term and finding the error in the sequence are asked.

  • On an average 1-2 questions are asked every year, though there were no questions asked from concepts related to Number series in SSC CGL 2016 Tier I.
  • Difficulty level of questions tends to be in between easy to moderate, with one of the major aspects being consumption of time.

Types of Questions Asked

Almost infinite numbers of patterns are possible in the Number Series Questions. Given below are patterns of some of the frequently asked questions in SSC CGL Examination.

  1. Prime Numbers:

A series of prime number constitute the sequence.

Example: 2,3,5,7,9

  1. Alternate Prime Numbers

A series of alternate prime numbers constitute the sequence.

Example: 2, 5, 9, 13

  1. Squares/ Cubes:

A series of perfect squares and cubes constitute the sequence.

Example: 8, 27, 64,125

  1. Patterns in differences:

A pattern is established wherein the difference between consecutive numbers in the sequences is a constant.

Example: 1,4,7,10,13 (difference between consecutive numbers is 3, therefore the following number will be 16)

  1. Pattern where number is sum of the previous two numbers

A pattern is established where the next number is obtained as the sum of the preceding two numbers.

Example: 2, 3, 5,8,13 next number is 13+8=21)

  1. Pattern where number is product of the previous two numbers

In this type, the next number is obtained as the product of the preceding two numbers.

Example: 1, 2,2,4,8

  1. Odd one out:

In this type, the sequence consists of one number that does not fit the pattern established by other numbers in the sequence.

Example:  5, 10, 12, 15, 20 (here all numbers except, 12 are multiples of 5)

  1. Pattern where difference between adjacent numbers is increasing/ decreasing by a constant number

In this type, the pattern is set by differences in consecutive numbers. The differences are increasing/ decreasing by a constant number.

Example: 1, 7, 19, 37 (difference between the numbers is 6, 12, 18, hence the difference between next numbers has to be 24, which means next number will be 61)

  1. Pattern where adjacent numbers are multiplied in a sequence

In this type, the sequence consists of numbers which are obtained after being multiplied by an increasing/decreasing sequence.

For example – 2, 4, 12, 48… (Here the first number is multiplied by 2, the second number by 3 and the third number by 4, hence next number has to be multiplied by 5, which means next number will be 240)

  1. Complex series:

In such cases, the pattern is established by differences between numbers. Rather than the differences between consecutive numbers being fixed, the differences exhibit a dynamic pattern. There is still a well defined logical rule that the sequence follows.

Example: 4,11,31,90




And hence next number will be 90*3-4=266

SSC CGL Number Series Preparation Tips

  • Thorough and regular practice reduces time consumed in solving questions.
  • Understanding logic behind different sequences may take a little bit of effort and time initially, but once topics are completely understood, Number series section becomes one of the easiest sections.

How to solve Number Series Questions in SSC CGL?

  • First, go through the given sequence slowly and check if there are any familiar numbers in the given series. Familiar numbers include numbers which easily recognizable like primes numbers, perfect squares, cube.
  • If there is no such familiar number in the sequence, subtract consecutive numbers in the sequence and check if any pattern emerges in the differences.
  • If the pattern in differences exhibits a slow growth the sequence may be an addition or subtraction series. If pattern in differences show a rapid change in growth, the sequence might be a square series, cube series, or multiplicative series.
  • If there are no familiar numbers in the sequence and if there is no clear pattern in the differences of consecutive numbers, then check every alternate number to see if they form any pattern.
  • Possible patterns include sum or the average of two consecutive numbers giving the 3rd number in sequence.
  • If a clear cut pattern is still not established, the given sequence is a complex sequence. It takes up some time to establish the relationship that drives the sequence.
  • Check for cases like multiplying the number and adding/subtracting a constant number from it to reach the pattern.

Challenges Faced by Students

One of the major challenges faced by students when solving questions from Number Series concepts is the management of time. These questions might consume loads of undue time thereby leaving candidates with little or no time for questions from other high scoring concepts.

Since most of the questions are framed from basic fundamentals, the question themselves do not seem tough to solve. But at times, figuring out the logic behind a sequence can be tricky. Time management of such sections can have a huge influence in the overall score of candidates.

It therefore becomes vital for candidates to be well versed with all possible types of questions from Number Series and practice tough questions on a daily basis to improve speed and accuracy.

Sample Questions

What should come in place of the question mark (?) in the following number series? 2916, 972, ? , 108, 36, 12
321234324 (Ans)None of these
The wrong term in the sequence 7, 28, 63, 124, 215, 342, 511 is
728 (Ans)124215
What will come in place of question mark in the following number series? 8,27,125, ? , 1331
234516216343 (Ans)
In the following question, identify the wrong number in the series. 5, 13, 29, 61, 120, 253
120 (Ans)2346129
Choose the correct alternatives from the given ones to complete the series: 1, 5, 4, 10, 8, 15?
12 (Ans)191714
Given below is a series which is incomplete, which of the given alternatives completes the series? 2, ?, 8, 16, 32
4 (Ans)657

Recommended Text Books

Name of the bookAuthorPublisherISBN
Quantitative Aptitude for Competitive ExaminationsR.S. AggarwalS.Chand8121924987
SSC Mathematics Topic-wise Latest 32 Solved Papers (2010-2016) Disha Experts TeamDisha Publications9386323230

Reference Website

Candidates can visit the following websites which have dedicated sections towards addressing basics of number series, tips to solve number series, sample questions. Candidates can practice all the material there to get a firm grip over all concepts and aspects related to number series.



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