Solution: PH7: Numerator, Denominator, Fascinator
Answer: BOO

Written by Dana Young

In order, the hats are:

WearerLength
Minerva McGonagall17
Jayne5
Uncle Sam8
Davy Crockett12
The Man with the Yellow Hat22
Magneto7
Mad Hatter9
Loki4
Marvin the Martian16
Guinan6
Carmen Sandiego14
Santa Claus10
Sherlock Holmes14
Ash Ketchum10
Gandalf7
Jafar5
Finn the Human12
Tin Man6
Willy Wonka10
Waldo5
The Cat in the Hat14
Hermes6
Turd Ferguson12
Goofy5


Overall, the math boils down to:

800, in the provided calculator font, looks like BOO (the answer).