How many 3 digit no. Can be formed by using the digits 1 to 9 If no digit is respected?

How many 3 digit no. Can be formed by using the digits 1 to 9 If no di

1.	How many 3 digit no. Can be formed by using the digits 1 to 9 If no digit is respected?
Answer» A three digit number is to be formed from given\xa09\xa0digits\xa01,2,3,4,5,6,7,8,9.□□□HTO⇒Now, there are\xa09\xa0ways to fill\xa0Ones\xa0place.⇒Since repetition is not\xa0allowed, so\xa0Tens\xa0place can be filled by the remaining\xa08\xa0digits.So, tens place can be filled in\xa08\xa0ways.⇒Similarly, to fill\xa0Hundreds\xa0of places, we have\xa07\xa0digits remaining.So, hundreds\xa0can be filled by\xa07\xa0ways.⇒So, the required\xa0number of ways in which three-digit numbers can be formed from the given digits is\xa09×8×7=504<br>A three digit number is to be formed from given\xa09\xa0digits\xa01,2,3,4,5,6,7,8,9.⇒Now, there are\xa09\xa0ways to fill\xa0Ones\xa0place.⇒Since repetition is not\xa0allowed, so\xa0Tens\xa0place can be filled by the remaining\xa08\xa0digits.So, tens place can be filled in\xa08\xa0ways.⇒Similarly, to fill\xa0Hundreds\xa0of places, we have\xa07\xa0digits remaining.So, hundreds\xa0can be filled by\xa07\xa0ways.⇒So, the required\xa0number of ways in which three-digit numbers can be formed from the given digits is\xa09×8×7=504