And the really annoying thing is that this error happens even though the writer got it right.
On a computer keyboard, the apostrophe key and the key you use to make a single quotation mark are one and the same. Just to the right of the semicolon key is the button we use all the time to insert apostrophes with no problem whatsoever — especially in contractions. Type “it’s,” “who’s,” “let’s” or “they’re” in Microsoft Word or similar word-processing software and the end result is probably exactly what you were aiming for: a little dagger-looking mark squeezed between letters that indicates something omitted.
Many word-processing problems curve the mark just a wee bit, giving the text a more polished look. Microsoft Word calls this a “smart quotes” feature and, unless you tell your computer otherwise, it automatically makes this change for you.
Most people never give this a moment’s thought and never have a problem with it. Indeed, most people could probably go their whole lives and never even notice.
Of course, most people don’t work as proofreaders, so they don’t realize just how vexing that little curvature can be in certain cases. You see, when the apostrophe comes in the middle of a contraction, these word-processing programs will curve it slightly to the left. But when it comes at the beginning of a word or a number, the program will curve it like the letter C, with the opening to the right, which actually changes this mark from an apostrophe to an open single quotation mark.