I'm new to Fallout New Vegas. I've gotten into and killed Pauline and sammy. I know the combination to the safe but how do I use the combination? I can't pick the lock. Is there something I'm missing? Some help would be awesome! Thanks

http://fallout.wikia.com/wiki/Pauline_Wins

"There is no Karma or reputation loss for killing both of them and taking their hats, but they do not drop a key to the safe when they die. The PC must either pass the Speech check of 55 or pick the very hard lock that requires 100 in Lockpick if they wish to open the safe and retrieve http://fallout.wikia.com/wiki/Vance%27s_9mm_submachine_gun."