Permutaion and Combination Methods

Permutaion and Combination Methods:
Permutation and combnation methods related math calculation are given in bank exams so its important to learn for exams We can't ignore it. So it is very very important to you improve your maths skills for banking exams in permutation and combination methods.Here is some general rule and formula are given,

In maths exam papers there are two or three question are given from this chapter.This type of problem are given in Quantitative Aptitude which is a very essential paper in banking exam.Under below  given some more example for your better practice.




General Rule and Formulae
Permutation and combnation methods related math calculation are given in bank exams so its important to learn for exams.
Factorial Notation : Let n be a positive interger..Then,Factorial n,denoted by ⌊n or n!  is defined as :

• n! = n ( n - 1 ) ( n - 2 ) ................3.2.1.

1. Ex. 5! = ( 1 x 2 x 3 x 4 x 5 ) = 120;
2. Ex. 4! = (1 x 2 x 3 x 4 ) = 24;
3. Ex. 3 = ( 1 x 2 x 3 ) = 6;

• 1! = 1
• 0! = 1

Permutation : The different arrangments of a given number or things by taking some or all at a time , are called Permutations.

•  All permutations (or arrangements) made with the letters of a, b, c by taking two at atime are ( ab, ba, ac, ca, bc, cb )
• All permutations made with the letters a, b, c, taking all at a time are : ( abc, acb, bac, bca, cab, cba ).

Number of Permutations : Number of all permutations of n things, taken r at a time, is given by :
ⁿ p r = n ( n - 1 ) ( n - 2 )......(n - r + 1 ) = n! / ( n - r ) !

1. Ex.⁶ p ₂
   = ( 6 x 5 ) = 30 .
2. Ex.⁷ p ₃
   = ( 7 x 6 x 5 ) = 210 ;

Note: Number of all permutation that is n things, we can take all at a time = n!

Examples: 6! / 2! = 1 x 2 x 3 x 4 x 5 x 6 / 1 x 2 = 360

Here is some Permutation and Combination important link which provided you better understanding.



Few examples of Permutation Shortcut Tricks

• Permutation examples 1 with tricks

• Permutation examples 2 with tricks

• Permutation examples 3 with tricks

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