Its not a guarantee. Although the girl at the front desk of the Boardwalk indicated that was the number "in the system", whatever that meant.
Actually, the reason she gave the number was, I want to send flowers down to the room and a food basket.
I (unfortunately) won't be staying, but some family will and I wanted to send along some "cheer" to help celebrate a special occasion.
She also advised to re-check the day of check in to advise the deliveries the actual room number.