How do you write #3,500,000,000# in scientific notation?
Scientific notation requires a decimal to the right of the left-most non-zero number.
If there is no decimal, place a decimal to the far-right of all of the numbers:
Now move the decimal to the left until it resides to the right of the left-most non-zero number. Count how many places the decimal has moved:
Remove the extra zeros unless this is a measurement: