Scientific notation is of the form . The value of bb tells you how many places and in what direction the decimal point of aa needs to be moved to convert the number to standard notation. If b<0b<0, then you need to move the decimal point to the left. If b>0b>0, you need to move the decimal point to the right.
For , we have b=−4. Since −4<0, we then need to move the decimal point of a=2 four places to the left. Moving the decimal place of a=2 four places to the left gives: