Nah, it's easier than that. The number is encoded in the hull transom number. There's a nice article on figuring it out in the Laser Wiki or TLF Knowledge Center. http://wiki.laserforum.org/index.php?title=Sail_Number
ZIDD2906A888
ZID represents the builder, then the next D stands for 13 and the next four digits are part of the sail number. So your sail number is 132906.