How many 3-digit numbers can be formed from the digits 0, 1, 3, 5, 7, 9 when no digit is repeated? How many of them are divisible by 10 ?

Answer

100

Explanation

The hundred's place cannot cannot contain 0. So, it can be filled by any of the digits 1, 2, 3, 5, 7.
So, there are 4 ways to fill it.
Now, each of the ten's and unit's digits can be filled by any of the given five digits.
So, each can be filled in 5 ways.
`therefore " the required number of numbers"=(4xx5xx5)=100.`