Counting

We opened a new book last night before bed like we have been doing each night of December.  I numbered the books so we could use them as a countdown.  And I make Alex tell me what number is on the book.  Last night, Travis happened to be in the living room for this little ritual.  

Alex picked up the book, I asked him what numbers were on it, he responded, "a 1 and a 6."  To which I agreed, let him know when they are written together like that it's a 16, and proceeded to say, "So there are 16 more days until Christmas."  I thought nothing of it since I was confident in my ability to number books from 25 to 1.  Travis looked at me funny and inquired, "...but...isn't today the 11th?"  Yes, yes it is.  

I don't know where I went wrong.  I don't know if I labeled the books incorrectly or if I have forgotten to have him open a book two different nights over the past 11.  Either way, apparently I am planning on having Christmas on the 27th this year.  You can all change your plans accordingly.