Question 994958
You have 7 digit choices. For the most significant digit choosing a 0 makes no sense. There are really only 6 choices for the highest order digit.

That leaves 6 digits (0 is ok now) for the next position.
5 digits for the third
4 digits for the 4th
3 digits for the 5th
2 digits for the 6th place.

Now multiply 

{{{TotalOfDifferentNumbers = 6 * 6 * 5 * 4 * 3 * 2}}}

you do the rest!