SOLUTION: how many three digit numerals for numbers divisible by five can be formed from the digits 0,1,2,3,4,5,6 if no digit may be used more than once

We have two choices for the last digit, 0 or 5.  However the first
digit cannot be 0, so we must take the situations when 0 is the last
digit separate from the situations when 5 is the last digit.

1.  When 0 is the last digit:

We can choose the first digit any of these  6 ways {1,2,3,4,5,6}
We can then choose the middle digit any of 5 ways.

That's 6·5 or 30 ways.

2.  When 5 is the last digit:

We can choose the first digit any of these  5 ways {1,2,3,4,6}
We can then choose the middle digit any of 5 ways (since it can be 0).

That's 5·5 or 25 ways.

The total is 30+25 or 55 ways.

Edwin