Formulae
Series:
The terms or elements follow a definite law in series but it cannot be generalized. You should know, what is the definite relationship between numbers which make the set of given terms in series. Addition, subtraction, multiplication, division, transposition of terms and series generally form such series. The different questions asked may depend upon the following:
1. Odd number/Even number/Prime numbers
The series may consist of odd numbers /even numbers or prime numbers except one number, which will be the odd man out. Hence, before solving numerical on this topic must revise all basic concepts.
2. Perfect squares/Cubes:
Squares: 9, 16, 49, 81 ….
Cubes: 27, 64, 125, 216 ….
3. Multiple of numbers:
The series contains numbers which are multiple of different numbers.
Example: 4, 8, 12, 16, 20…..
4. Numbers in A.P./G.P.
Geometric progression: x, xr, xr3, xr4
Arithmetic progression: x, x + y, x + 2y, x + 3y are said to be in A.P.
The terms in series may be arithmetic or geometric progression.
5. Difference or sum of numbers:
The difference between two consecutive numbers may increase or decrease
6. Cumulative series:
In this type, the third number is the addition of previous two numbers.
Example: 2, 4, 6, 10, 16, 26 ……
7. Power series:
In this type, the terms are defined on the basis of powers of numbers; the number may be expressed in the form of n3 – n.
Example:
If n = 4, n3 – n = 60
If n = 5, n3 – n = 120…
Series: 60, 120, 210, 336 …
8. The middle digit is the sum of other two digits.
Example: 165, 121, etc
9. The series of numbers may follow different sequence as shown below:
(n2 – 1), (n2 + 1), (n2 – n), (n3 – n), (n2 – n + 1), (n2 – n – 1), etc
a) If numbers in the series are 1,5, 11, 19, 29…. then the relation is (n2 – n – 1)
b) If numbers in the series are 21, 31, 43 then the relation is (n2 – n + 1)
Example:
If n = 5, (52 – 5 + 1) = 21
If n = 6, (62 – 6 + 1) = 31
If n = 7, (72 – 7 + 1) = 43
Exercise : Odd Man Out and Series MCQ Questions and Answers
Questions will be uploaded soon.