The Sound of 1,100

       The movie "Wild" was listed in a broadcast schedule and described thus:  "A lone woman undertakes an 1,100 mile hike."

        Why use “an” when there are numerals afterwards?  If you say it as I did, "one thousand one hundred." then the sound [wuh] for "one" is there,  a consonant sound; so "an" wouldn't apply. The article is "a." 

       Perhaps they figured it would be said,  “an eleven hundred mile hike. ”  But there's that comma.

       It depends on the sound that follows.  Maybe they thought, "It begins with the numeral 1--treat it like language spelled 'o,' 'n,' 'e,'  and since 'o' is a vowel, we'll use 'an' to make it sound right."

       Except the letter "o" isn't what's operative!  It's the sound of the word "one," which begins [wuh], exactly as in the word "won."