Significant Figures Question

[DarkMagus]

Another way of thinking about it is that you can get more accurate measurements of a thing by measuring in different ways even if you're using the same tools to measure.

Say you want to measure the diameter of a penny but for some reason you only have a ruler that is subdivided into centimeters. Well, by lining up 10 pennies, then measuring that and dividing the length by 10, you can get a measurement that is just as accurate as if you had a ruler subdivided into millimeters. Same idea with the circle: you can measure the diameter with a higher % accuracy than the radius.