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Basics of Permutation and Combination (in Hindi)
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Permutation and combination, How to count easily

## Manoj Chauhan is teaching live on Unacademy Plus

Manoj Chauhan
Maths faculty for IIT JEE (Main and Advance), Maths Specialist for Calculus, Ex Senior faculty Vibrant Academy,Top notch online faculty

mam, upsc cse ke attempt m state pcs ke attempt count honge kya ???😊👍👌
Charu Modi
a year ago
hi Sachin, no they are not counted
Santosh Jain
8 months ago
great genius
Santosh Jain
8 months ago
great genius
Santosh Jain
8 months ago
great genius
Santosh Jain
8 months ago
great genius
sir is anything is left after this course of p&c plzzz sir tell
love you
sir mera class 10th me 43% hai to kya iit me addmission ho jai ga agar 75% + aie ga to...
sir physics ke liye best faculty on YouTube and also on unacademyfoe iit
Manoj Chauhan
2 months ago
2 months ago
sir mera class 10th me 43% hai to kya iit me problem ho sakta hai...
2 months ago
plz
1. PERMUTATIONS AND COMBINATIONS INTRODUCTION Suppose you have a suitcase with a number lock. The number lock has 4 wheels each labelled with 10 digits from 0 to 9. The lock can be opened if 4 specific digits are arranged in a particular sequence with no repetition. Some how, you have forgotten this specific sequence of digits. You remember only the first digit which is 7. In order to open the lock, how many sequences of 3-digits you may have to check with?

2. To answer this question, you may, immediately., start listing all possible arrangements of remaining digits taken 3 at a time. But, this method will be tedious, because the number of possible sequences may be large. Here, in this Chapter, we shall learn some basic counting techniques which will enable us to answer this question without actually listing 3-digit arrangements. In fact, these techniques will be useful in determining the number of different ways of arranging and selecting objects without actually listing them. As a first step, we shall examinea principle which is most fundamental to the learning of these techniques.

3. The factorial Factorial Notation Let n be a positive integer. Then, the continued product of first n natural numbers in called factorial n, to be denoted by n !, or n. Also, we define 0 ! 1. When n is negative or a fraction, n! Is not defined. Thus, n ! = n (n-1) (n-2) 3.2 . 1.

4. Q. 6.=(6 5 4 3 2 1) = 720, 3, = 3 2 x 1 = 6 and 1 ! = 1.

5. Solution =n(n-1)(n-2)(n-3) 3. 2 . 11 Thus, we have (i) n!- n (n -1) (n - 2)... 3 x 2x 1.

6. Q. Compute: 10! 30! 11!-10! (71)-(31) (6) HI 10

7. Solution We have 10!10x9x8x(7!) 10x9x8 (7)x(3!) (7!)x(3x2x1) 3x2xl = 120 30! 30x 29x (28!) (ii) 28! =-(28!) 30 29 = 870 119:10: 11-10-191.-10. 9:) . (110-10)(91. (9!) 100