Removing text from numbers

I have a column of data which has numbers and units (small example below). I need to remove the text (units) and at the same time multiply the number by a value which is based on what the text is:

-999.9uA needs to become -999.9*10^-6

-98.40mA needs to become -98.40*10^-3

etc. Can anyone help?

Thanks!