But then Des would've known the number whilst all of this was going down on the freighter. But I think he only knew the number after the last time his brain time travelled. I don't think he knew it on the island and on the freighter, talking with Minkowski, etc and simply couldn't remember until the last second there. That doesn't make sense to me. I think that once his 2004 mind left his 1996 body walking away from Penny's place, 1996 Des became oblivious to the whole thing. That is the only way it makes sense to me. I hate time travel.