Math Question: see + you = soon

My little brother in grade 4 has this question for homework and my entire family cannot figure it out! We are supposed to subsitute the letter for a value. We need to find the value for S, O and N

Any help?

Hello,

    SEE
+  YOU
------------
  SOON

Hence:
{ E + U = N (+10?)
{ E + O (+1?) = O (+10?)
{ S + Y (+1?) = O (+10?)

We will suppose that S is not equal to zero, else the problem is absurd (why put a zero in front of a number?)
Then S=1.

This means then that:
1 + Y (+1?) = O + 10
Thus Y must be equal either to 8 or to 9 (depending on the carry), otherwise 1+Y(+1?) wouldn't get over 9. In any case O must be nil.
Thus O=0.

Since O=0, then
E + O (+1?) = O (+10?) becomes
E + 0 (+1?) = (+10?)
Thus we must have E=9 to have a carry toward previous equality.
Thus E=9.

Since 9 is taken by E, Y cannot then be anything else except 8.
Thus Y=8.

Now we finally have:
E + U = N + 10
9 + U = N + 10
U cannot be 0 since 0 is already taken by O.
U cannot be 1 since 1 is already taken by S.
U cannot be 2 since 9+2=11 and N would be equal to 1 which is already taken by S.
If U=3, N=2
If U=4, N=3
If U=5, N=4
If U=6, N=5
If U=7, N=6
U cannot be 8 since 1 is already taken by Y.
U cannot be 9 since 1 is already taken by E.

Hence, there are five solutions:
199 + 803 = 1002
199 + 804 = 1003
199 + 805 = 1004
199 + 806 = 1005
and 199 + 807 = 1006

Logically,
Dragon.Jade :-)

199
803
1002
possible answer
S=1, O=0, N=3
there are many possibilites

2 + 1 = 3