Example 10 - Chapter 6 Class 11 Permutations and Combinations

Last updated at Dec. 16, 2024 by

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Example 10(Method 1) How many 4-digit numbers can be formed by using the digits 1 to 9 if repetition of digits is not allowed? n = Numbers from 1 to 9 = 9 r = 4 Required 4 digit number = 9P4 = 9!/((9 4)!) = 9!/5! = (9 8 7 6 5!)/5! = 3024 Example 10(Method 2) How many 4-digit numbers can be formed by using the digits 1 to 9 if repetition of digits is not allowed? Let the 4 digit number be Number of 4 digit numbers which can be formed = 9 8 7 6 = 3024

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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science and Computer Science at Teachoo