1 minute question

Q: Having an expression:

A B C D
+ B C D
--------------
E F G H I

where each letter A-I represents different digit number 0-9.

Then which number is absent in above expression?

A: It is easy to see that E = 1, A = 9, F = 0,
we can also see that 5 can not be in BCDI, as otherwise either 0 or 1 will be in GHI.

if 5 in H, then C is 7, and BCD= 678 or 876 ==> 2*BCD = 1356 or 1752, which is not possible.
if 5 in G, then B is 7, and BCD =768 or 786==> 2*BCD = 1536 or 1572, which is not possible either.

so 5 is absent.