Marcus and Joe are correct regarding the US definition of the grade (English spelling), which is the French grad (1/100th of a right angle). This is another example of "hidden" metric that Americans have long used and understood, although many don't know it *is* metric!
In high school I was taught that definition. The math textbook said that only the first quadrant of the unit circle (0 - 100 grades [0� - 90�]) is commonly used, which is why grades are usually expressed as a percentage in the US. Our road signs use % grade, and my father used % grade when he built houses. -- Jason
