Explanation:
scientific notation is
a.b × 10^c
with a being <> 0.
0.0002 cm = 2.0×10^-4 cm (the "2" moves 4 positions to the right for the actual number).
so, this is between 1.0×10^-4 cm and 1.0×10^-3 cm.
0.02 cm = 2.0×10^-2 cm (the "2" only need to move 2 positions to the right for the actual number).
so, this is between 1.0×10-2 cm and 1.0×10^-1 cm.
200 cm = 2.0×10² cm (now the "2" needs to move 2 positions to the left for the actual number).
so, this is between 1.0×10² cm and 1.0×10³ cm.
20,000 cm = 2.0×10⁴ cm (the "2" has to move 4 positions to the left for the actual number).
so, this is between 1.0×10⁴ cm and 1.0×10⁵ cm.