If it is what chroot is suggesting it is, it looks hard to figure without using a computer. Making a few simple eliminations (O=0 or 9), reduces the number of possibilities to about 10^5 - notice that there are 10 different letters, so all the digits must be used. Hmmm...looks like a toughie.
Are you just making up a generic example off the top of your head, or is this the exact question from a book or homework ? If the former, there may be no solution at all, and even if there are solutions, they may not be paper-and-pencil-able.