"Time's up!" says the wizard. 

"This isn't fair!" you say.  "I'm not that good at math!  And why do I need to know math in order to be a good knight?  Sir Lancelot didn't need good math skills in order to best the Black Knight.  Saint George didn't need to know his times tables in order to slay the dragon.  It's just not fair!" 

"Stop whining," the wizard says.  "You passed the test." 

Your jaw drops two full inches.  "Huh?" 

"I timed how long it took you to come up with an answer.  If you had cheated -- by pencil or paper, or abacus, or simply by guessing -- you would have come up with an answer much sooner.  By taking as long as you did, I knew that you were being honest and trying to come up with the answer through your own efforts.  Therefore, by taking as long as you did, you proved yourself a knight of integrity and worthy to pass the test." 

"Well, what if I was really good at math?" 

"Then you would have given the correct answer in less time than I anticipated for you to take, and I would have assumed you were lying, and you would have failed the test." 

"So . . . by being lousy at math, I passed your test?" 

"Yep," replies Turing the Tester. 

"And you think that's right?" 

"If people were good at math, the Dark Ages would end and where would us wizards be?" 

He's right you know.  His wizard's staff may shoot bolts of lightning, but it's not very accurate and range is limited.  It's no match for a modern automatic field rifle, let alone a fiber-optic guided anti-tank missile. 

"I'll thank you to keep your twenty-first century references to yourself," you say. 

"Who are you talking to?" the wizard asks. 

"The narrator," you reply. 

"The who?" 

"Never mind.  So I can use the bridge now?" 

"Go for it, kid." 

You nod, and cross over the chasm.