Number Series

Number series is one of the most important topic usually asked in SSC exams. We are providing some brief idea about number series with the help of examples.

What is Number Series?

Number series is a sequence having some pattern of sequence in it, where numbers relate to each other in certain mathematical way.

In exams questions related to number series are given in two different ways.

1. To find next number / missing number of sequence.

2. To find number mistakenly put into the numbers series/ Wrong number.

3. To solve these questions you need to find the pattern of relation, of numbers

How to solve questions on “Next term of Number Series”?

(I) In questions on number series numbers are connected to each other in certain mathematical way. Find the pattern of relation within the numbers.

(II) Apply the same pattern to find next term.

How to solve questions on “Wrong term of Number Series”?

(I) In case of wrong number series observe numbers carefully and try to find a set pattern of relation within numbers

(II) The number which will not follow the relation as of other numbers (Previous and Next) that will be the wrong term of that series

Most frequent Patterns of “Number Series” related questions

(1) Prime Number Series: In a series where numbers are a series of prime numbers 

For example – 7, 13, 19, 27, ?

Explanation- Alternate prime numbers are given starting from 7 so next term will be 31

(2) Squares/ Cubes Series: when numbers are a series of perfect square or cube roots.

For example – 49, 64, 81, 100, 121, ?

Explanation- Square of 7 is 49, Square of 8 is 64, Square of 9 is 81 and so on.. So net term will be Square of 12 is 144

(3) Systematic Difference Series: When the numbers of a series are on a set difference.

For example – 3, 5, 8, 12, 17, ? 

Explanation- Starting from 3 the difference is 2, then difference is 3, then 4, then 5, so next difference will be 6 hence next term (answer) should be 23

(4) Alternate number Pattern Series/ Mix Series: In such series every alternate numbers are being related in a certain pattern and it seems like two different series are merged. 

For example – 7, 9, 10, 13, 13 , 17, 16, ?

Explanation- In this series alternate numbers 7, 10, 13,16 are at a difference of 3, and 9,13, 17, are at a difference of 4

So next term will be 21.

(5) Geometric series: In such series every next number is obtained by multiplying or dividing the previous number by a fixed number/set pattern of number.

For example – 8, 48, 288, 1728, ?

Explanation- In this series next number is sixth multiple of previous number so answer will be 1728*6 = 10368

For example – 3, 6, 18, 72, ?

Explanation- In this series next number is multiple of set pattern of number and producing next number 3*2 = 6, 6*3 = 18, 18*4 = 72, So 72*5 = 360

(6) Cube roots/ square roots: In such number series numbers are in a series of cube roots and square roots.

For example – 343, 729, 1331, 2197, ?

Explanation- In this series Numbers are cube of every alternate number starting from cube of 7 = 343, cube of 9 = 729, cube of 11 = 1331, cube of 13 = 2197, so next term will be cube of 15 = 3375,

For example – 121, 169, 289, 361, ?

Explanation- In this series Numbers are square of every alternate prime number starting from square of 11 = 121, square of 13 = 169, square of 17 = 289, square of 19 = 361, so next term will be square of 23 = 529,