Ex 7.3, 1 - How many 3-digit numbers can be formed - Chapter 7 - Permutation- non repeating

  1. Chapter 7 Class 11 Permutations and Combinations
  2. Serial order wise
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Ex 7.3, 1 (Method 1) How many 3-digit numbers can be formed by using the digits 1 to 9 if no digit is repeated? n = numbers from 1 to 9 = 9 r = 3 Required 3 digit numbers = 9P3 = 9!/(9 − 3)! = 9!/6! = (9 × 8 × 7 × 6!)/6! = 9 × 8 × 7 = 504 Ex 7.3, 1 (Method 2) How many 3-digit numbers can be formed by using the digits 1 to 9 if no digit is repeated? Let the 3-digit number be Number of 3 digit number which can be formed = 9 × 8 × 7 = 504 ways

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