1. The problem statement, all variables and given/known data What is the approximate uncertainty in the area of a circle of radius 5.3 * 104 cm? Express your answer using one significant figure. 2. Relevant equations A = pi*r2 3. The attempt at a solution Using the given radius, I found the area to be 8.8 * 109 cm2. And since the uncertainty is not given, I'm assuming that it's 0.1 * 104 cm. Using this, the upper limit for the radius is 5.4 * 104 cm, which makes the upper limit for the area 9.2 * 109 cm2. Subtracting 9.2 - 8.8 = 0.4 * 109 cm2. But this is apparently not the correct answer, and I can't figure out why. Unless I'm forgetting some fundamental aspect of significant figures, the only other way I can express this in one sig fig is to write out the actual number, i.e. 400000000; but this is also incorrect. What am I doing wrong?