Question

The radius of Mercury is approximately 2 × 103 kilometers, and the radius of Uranus is approximately 2 × 104 kilometers.

To determine approximately how many times bigger the radius of Uranus is than the radius of Mercury, Ken performs the following operation.



Approximately how many kilometers bigger is the radius of Uranus than the radius of Mercury?

A.
10
B.
180
C.
9,000
D.
18,000

Answer 1

Radius difference = 2×10^4 − 2×10^3 = 2(10,000 − 1,000) = 2×9,000 = 18,000 km.

Answer: D.