Answer: 4.5e-4
Explanation:
To convert to scientific notation, move the decimal place to create a number between 1 and 10. In this case that number is 4.5.
To get to 4.5 you had to move the decimal 4 places forward. This means your exponent is 4. Since the number being put into scientific notation(0.00045) is less than 1, the exponent is negative.
In regular scientific notation it looks like this:
[tex]4.5*10^{-4 }[/tex]
In E format, it looks like this: 4.5e-4
The e is just a short form for "times 10 to the power of"