Question

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

Answer 1

Total number of digits = 6
We cannot have 0 at the first digit of the required six-digit numbers.
The digits cannot repeat in the six digits number.
$\therefore$ total number of six digit number are = $5\times 5\times 4\times 3\times 2\times 1=600$
Now, the six digit number can be divided by 10, if its last digit is 0
$\therefore$ Total numbers which are divisible by 10
= $5\times 4\times 3\times 2\times 1\times 1=120$