Question

find the number of numbers of 6 digit without repetition formed with the digit 123456 in which 5 always occurs in tenth place

Answer 1

Step-by-step explanation:

On the tenth place, 5 is fix. And repetition is not allowed.

1. Put 5 on the tenth place.

Now we have only 5 different no. and also five different places to fill.

so,

2. For onec place, we have 5 different numbers. so we can put any of the remaining 5 numbers.

3. 10th place is fill, so we need to fill hundredth place.

Now, we have 4 remaining places and also 4 remaining numbers.

So for 100th place, we can put any one from remaining 4 numbers.

4. For 1000th, we have 3 numbers, .....

......

....

and so on.

finally , we get the situation of

1×2×3×4×1×5 = 120.

Answer = 120