Write 307,000 in scientific notation.
This time, there is a zero that is a significant digit. Be sure to include this in the coefficient.
Move the decimal until you get a number between 1 and 10
Only drop the three zeros that come after 7. You can't drop the zero that comes before the seven without changing the value of the number.
Multiply by 10 to the fifth power, since you moved the decimal five places.