Answer
$1.0\times10^{-3}$
Work Step by Step
We are given that the rate of pulses for a pulsar is every .001 second.
Step 1: To write this number in scientific notation, we move the decimal point to the right until the original number is 1.0.
Step 2: Since the original number was less than 1, we moved the decimal by 3 negative places. In other words, we will raise 10 to a power of -3.
Now, we write the product of the two numbers found in Step 1 and Step 2.
$1.0\times10^{-3}$