I have no advice for the OP, but on Waynewongs point this is a good idea and something I do because I know that eventually I will forget the number.
When you get a new safe be sure to leave the safe numbers somewhere in the house and in plain sight. You do this so that someone else can open the safe if you happen to keep papers or certs in it. Just make an entry into your telephone book or your cell phone, telephone pad is better since you can lose your cell phone.
For this example I'll use an area code and safe combo number. 781 and 37,81,17. The dummy telephone entry for that would be:
Bill Smith 781-378-1177. The last digit is just a repeat of the last digit of the combination.
Hope that helps someone.