Question

How do you write `.0000000009` in scientific notation?

Answer 1

I got `9xx10^-10`

Explanation:

You must move the point to the right counting how many positions you moved up to passing the first non-zero digit (`9`):
Here you move the point of `10` positions.
You then have:
`9xx10^-10`
Where the right movement is represented by the minus sign and the number of positions by the numerical coefficient of `10`.