A letter of the alphabet?
A number between 23 and 24.5?
Punctuation that isn't an apostrophe?
An incorrectly spelt word?
The next number in this sequence: 6 9 15 18 24 __?
1+1+1+1+1x0+1+1+1=?
A crying, happy face?
e=mc__ Fill the gap?
The blank square?
The date in December on which Christmas falls?