O = Odd, E = Even

In the following sum the digits 0 to 9 have all been used, O = Odd, E = Even, zero is even and the top row's digits add to 9. Can you determine each digit?

 

 

Answer:

Remembering that:
    E + E = E
    O + O = E
    E + O = O
To discuss individual letters it's easiest to represent the sum as:
    A B C
    D E F +
 --------
  G H I J
The largest values for A and D are 6 and 8, which makes G = 1.
 Since column 2 is E + O = O there can be no carry from column 1 (since E + O + 1 is always even). Therefore C and F are 3 and 5 (but we don't yet know which is which), therefore J = 8.
 There can't be a carry from column 2 (as A + D is even) therefore E can't be 9 as this would force a carry.
 Therefore I = 9. Hence B can't be 0. Therefore H = 0.
 The last remaining odd number makes E = 7. Making B = 2.
 Therefore A and D are 4 and 6 (but we don't yet know which is which).
 Since the top row's digits have to add to 9 the top number must be 423.
 This makes the sum 423 + 675 = 1098.