There are total 6 digits available ,for forming a 6 digit number,in 100000’s place only 1,3,5,7,9 can be used(0 not included because it will lead to formation of 2 digit number.)

In 10000’s place any of the remaining 5 digits can be used(even 0 can be used.)

In 1000’s place any of the remaining 4 digits can be used.

In 100’s place any of the remaining 3 digits can be used.

In 10’s place any of the remaining 2 digits can be used.

In one’s place the remaining digit can be used.

So total number of 6 digit numbers possible=5 × 5 × 4 × 3 × 2 × 1=600

For finding the number of 6 digit numbers divisible by 10 the one’s place should contain 0 so possibilities=5 × 4 × 3 × 2 × 1=120