How many 3-digit numbers can be formed by using the digits 1 to 9 if no digit is repeated?

Solution:

We have to find the number of 3-digit numbers that can be formed by using the digits 1 to 9 if no digit is repeated.

The given number of digits = 9 (from 1 to 9).
No. of ways of choosing first digit = 9
Since no digit should be repeated,
No. of ways of choosing second digit = 8
No. of ways of choosing to third digit = 7

Using the fundamental principle of counting,
Total possible numbers of ways = 9×8×7 = 504

NCERT Solutions Class 11 Maths Chapter 7 Exercise 7.3 Question 1

How many 3-digit numbers can be formed by using the digits 1 to 9 if no digit is repeated?

Summary:

The number of 3-digit numbers that can be formed by using the digits 1 to 9 if no digit is repeated is 504