NCERT Class XI Mathematics - Permutations and Combinations - Solutions

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Question : 11
Total: 41
How many 3-digit numbers can be formed by using the digits 1 to 9 if no digit is repeated?
Solution:  
Total digits are 9. We have to form 3 digit numbers without repetition.
∴ The required 3 digit numbers =
9
‌
P3
= 9 × 8 × 7 = 504
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