Aptitude - Permutation and Combination - Discussion
Discussion Forum : Permutation and Combination - General Questions (Q.No. 7)
7.
How many 3-digit numbers can be formed from the digits 2, 3, 5, 6, 7 and 9, which are divisible by 5 and none of the digits is repeated?
Answer: Option
Explanation:
Since each desired number is divisible by 5, so we must have 5 at the unit place. So, there is 1 way of doing it.
The tens place can now be filled by any of the remaining 5 digits (2, 3, 6, 7, 9). So, there are 5 ways of filling the tens place.
The hundreds place can now be filled by any of the remaining 4 digits. So, there are 4 ways of filling it.
Required number of numbers = (1 x 5 x 4) = 20.
Discussion:
89 comments Page 4 of 9.
Pravas said:
9 years ago
Shortcut way to solve this problem :-6C3 => 6!/3!
= 6 * 5 * 4/3 * 2 * 1.
= 20.
= 6 * 5 * 4/3 * 2 * 1.
= 20.
Akhil said:
10 years ago
Thanks @Rahul! good explanation.
Justin said:
9 years ago
The best way is,
6c3 = 20.
6c3 = 20.
Karthick said:
9 years ago
How many 4 digit no can be formed with digits 1, 2, 3,4,5 which are divisible by 4 and digits not repeated?
a)144 b) 168 c) 182 d) none
Please tell me the correct answer.
a)144 b) 168 c) 182 d) none
Please tell me the correct answer.
Joe said:
9 years ago
Why isn't it just 5C2, from the 5 numbers that arent 5 to go in tens and hundreds, and picking two?
Vignesh said:
9 years ago
Please explain me, what would happen if another digit (0) is added to the series, i.e., 2,3,6,7,9,5 and 0 and the digits are to arranged without repetition such that the 3 digit number is divisible by 5?
DharanG said:
10 years ago
There are 6 digits are given ,
As per question one(5) is fixed so 5! = 120.
Three digit number is going to be formed by 3! combination.
So, 120/6 = 20.
As per question one(5) is fixed so 5! = 120.
Three digit number is going to be formed by 3! combination.
So, 120/6 = 20.
Shantanu said:
8 years ago
How many five digit numbers can be formed by using digits 0, 1, 2, 3, 4 and 5 without repetition. And number should be divisible by 6.
Can anyone solve this?
Can anyone solve this?
Raoakc said:
8 years ago
Can't we do it by combination?
Brown said:
7 years ago
What if the series includes 0, ie 2 3 5 6 7 9 0?
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