Problem for elementary school -find letter a number such that - $SEND+MORE=MONEY$

Question

Problem: Find the number for every letter(different letter is a different number) such that this equality holds. $$SEND+MORE=MONEY$$ My solution: Because idea of this problem isn't to solve it's to show algorithm step by step and that algorithm present to the children in school.(so no hard maths).
It's easy to see that $M=1$ (in elementary school you couldn't say that but with showing possibilities ).
First case was that $S+M=9$ so that implies $S=8$(with carrying 1) if not $S+M=10$ , $S=9$. But the problem begin with next step letters $E,O$ because I didn't know anything about.