The original solution to this calculation is
shown above as Solution 1.
Though it is not stated in the rules directly, but it is implied zero
can't be the first digit in any of the three numbers. At the same time
if there is no such a restriction in the rules, then the solution sent
in by Becca Malburne (see Solution 2) is also valid.
Another our visitor, Monika S., has sent in a series of solutions
where M=0. They can be found
Many thanks for these contributions!