How do you express the number in scientific notation given the diameter of Neptune: 49,600,000 m?
Adjusted stepwise so that you can see what is happening:
In scientific notation there must be ONE digit (non-zero) before the decimal point and then a power of 10 to indicate the size of the number.
Count the number of places you move the decimal.
If it moves to the left, (as in this case) the power of 10 increases, if the point moves to the right, the power of 10 decreases.