Part of me wants to assume that you're telling the truth and it is a double digit. I wouldn't have a hope in hell of guessing what it is since no restriction was applied, e.g. a number between 1 and 10.
Another part of me noticed that you left out "a" before double - I'm not a spelling or grammar Nazi. Bear with me. A is the first letter in the alphabet, so that would mean your number is 1. Then again it could just be a typo.