Twilight is setting up for a sleepover, Pinkie brought over exactly 28 cookies for everypony at the sleepover. Pinkie claims that all 7 of them (including Spike) should have 13 cookies each. Pinkie’s math doesn’t make any sense to Twilight (or me) she and wants Pinkie to prove to her that 7 x 13 really does equal 28. (IT DOESN'T!!!!!)

The original story can be found here:
http://www.fimfiction.net/bookshelf/617854/to-read