Q.5.    How many 6-digit numbers can be formed from the digits 0, 1, 3, 5, 7 and 9            which are divisible by 10 and no digit is repeated?

For the number to be divisible by 10, unit digit should be 0.

Thus, 0 is fixed at a unit place.

Therefore, the remaining 5 places should be filled with 1,3,5,7,9.

The remaining 5 vacant places can be filled in $5!$ ways.

Hence, the required number of 6 digit numbers which are divisible by 10$=5!=120$

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