# while using permutations and combinations we use both multiplication and addition.in which all places will we use both these

SHAIK AASIF AHAMED
9 years ago
Hello student,
These two principles will enable us to understand Permutations and Combinations.In fact these two principles form the base of Permutations and Combinations.
1)Fundamental Principle of Multiplication
"If there are two jobs such that one of them can be completed in ‘m’ ways, and another one in ‘n’ ways then the two jobs in succession can be done in ‘m X n’ ways."
Example :- In her class of 10 girls and 8 boys, the teacher has to select 1 girl AND 1 boy. In how many ways can she make her selection?
Here the teacher has to choose the pair of a girl AND a boy
For selecting a boy she has 8 options/ways AND that for a girl 10 options/ways
For 1st boy ------- any one of the 10 girls ----------- 10 ways
For 2nd boy ------- any one of the 10 girls ----------- 10 ways
For 3rd boy ------- any one of the 10 girls ----------- 10 ways
-------------
------------
For 8th boy ------- any one of the 10 girls ----------- 10 ways
Total number of ways 10 + 10 + 10 + 10 + 10 + 10 + 10 + 10 = 80 ways OR 10 X 8 = 80 ways.
Remark :-The above principle can be extended for any finite number of jobs.