Answer
0.001$0$9$0$; cross out the first 3 zeroes and underline the last 2 zeroes
Significant zeroes above are bold.
Work Step by Step
The first 3 zeroes are insignificant because they are leading zeroes which serve a a place holder. The 4th zero is significant because it's an internal zero, and the last zero is also significant because it's a trailing zero
