Number Series Notes - 2 CAT Notes | EduRev

Type 3 - Factorisation / Prime Factorisation

If Type 1 and Type 2 is not applicable in a sequence, one must try to make factors of the numbers in the next step.

Example 1: 6, 15,35,77,143, __.
In the above example all the previous tricks are not applicable to get answer. Hence, We will make factors of the given numbers

(2,3,5,7,11,13) all are prime numbers in ascending order.
Hence, 13*17 = 221, is the correct answer.

Type 4 - Fibonacci Series

A series in which a number is made by using previous two numbers is called Fibonacci series.

Example : 1, 4, 5, 9, 14, 23, ___
In the above sequence all the numbers are sum of previous two numbers.
Therefore, 23+14 = 37, is the correct answer.

Type 5 – Sum of Digits

Example 1:

In the above sequence, difference between two numbers is the sum of digits of the first number.
Hence, 89 + 17 = 106, is the correct answer.

Example 2:

All the numbers are multiplied by their sum or added by their sum alternately. Therefore, 11788 + 25 = 11813, is the correct answer.

Type 6 – Alternate Pattern Series

When numbers given as a hint in a questions are more or when a question ask two numbers of a series or same number come twice in a series, these all give hint to alternate pattern series.
Example 1:

So, numbers are 12 + 5 = 17, 53 - 6 = 47
Ans. 17,47

Example 2:

So, the number is 24 + 3 = 27
Ans. 27

Type 7 - Decimal Pattern Series

When the numbers of the sequence are given in the decimal form is decimal pattern series.
Example 1:

So, the answer is 18*.8 = 14.4

Example 2:  16, 24, 60, 210, 945, __
The pattern is:
16*1.5 = 24
24*2.5 =60
60*3.5 = 210
210*4.5 = 945
945*5.5 = 5197.5

Type 8 - Bracket Pattern Series

While using bracket pattern we multiply first outside and either add or sub based on given no.

Example 1: 3, 28, 180,  ____,  3676
The pattern is : (3+1)*7 = 28
(28 + 2)*6 =180
(180 + 3)*5 = 915
(915 + 4)*4 = 3676
Ans. 915

Example 2: 37, 31, 52, 144, __, 2810 
The pattern is:
(37 - 6)*1 = 31
(31 - 5)*2 = 52
(52 - 4)*3 = 144
(144 - 3)*4 = 564
(564 - 2)*5 = 2810
Ans. 564

Type 9 - Dual Pattern Series

Example:
15,  9, 8, 12, 36, 170
19,  a, b, __,  d, e
The pattern is:
(15 - 6)*1 = 9
(9 - 5)*2 = 8
(8 - 4)*3 = 12
Similarly:
(19 - 6)*1 = 13
(13 - 5)*2 = 16
(16 - 4)*3 = 36
Ans. 36

Type 10 - Factorial Based Series

This is latest pattern question asked in latest exams
Example 1:

Ans. 33

Example 2:

Ans. 606 + 721 = 1327