Convert 0.001 to scientific notation

To convert to scientific notation, you must move the decimal to make the number greater then 1 and less then 10.

So you take your decimal and move it.

0.001
. -->

We move the decimal to before the 1 which gives us the whole number of 1.

Now we get:

1*10
(always *10)
and now you want to make this exponent how many times you moved the decimal, in this case 3.
This time its negative since we moved it to the right, moving to the left would make it positive.

Final  

The answer should be a