I had a friend back in college who wrote an entire term paper on the Medieval "futile" system. He got an A-minus. The prof deducted a few points for spelling, but told him his ideas pretty much worked with either spelling... /g
“Futile” system — that’s priceless!
It happens. I wrote a lengthy essay in college on Frederick Douglass and for the entire paper, I only put one s in his last name. The instructor also gave me an A- while informing me of the correct spelling. I was shocked because for all the times I read and looked at the name, my mind did not register the two s’s.