Question

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 ?

A) 15 B) 20 C) 5 D) 10

Answer 1

Answer:

As 3 digit number is divisible by 5, its unit place should contain digits 0 or 5. As you can see we have only 5 present here, put it in units place. Now you have 5 digits - 2, 3, 6, 7, 9 remaining.

So you can select 5 digits for tens place and as repeatation is not allowed, for hundreds place you can select remaining 4 digits. So final answer is 4 * 5 * 1 = 20 numbers can be formed.

OR

You can select 2 digits out of 5 digits given in C(5,2) = 20 ways. And as units place contain only 5, final answer becomes 20 * 1 = 20.

plz see above so u get idea

Answer 2

Answer: 20

Step-by-step explanation:

Since the no. is divisible by 5, so only 5 can be used in the unit's place.

For the ten's and hundred place, 4 and 5 digits are remaining (for no repetition) .

Hence final answer is given by = 1*5*4 = 20