Great responses. But for all practical purposes, one MOA is one inch at 100 yards. This is pure coincidence, of course, but is useful shorthand for discussing accuracy.
So 1 minute of Angle is about 2 inches at 200 yards, 3 inches at 300 yards, and so on, though that .047 adds up. So a rifle that shoots into one inch at 100 yards, will shoot into 10 inches at 1000? Probably not, since too many other factors enter in, such as the effects of wind, bullet shape, drift, etc.
Jim