The number 0.00045 in scientific notation is written as:

$4.5 \times 10^{-4}$

Would you like more details on how this conversion is done?

Here are 5 related questions you might find helpful:

1. How do you convert large numbers to scientific notation?
2. What are the rules for adding numbers in scientific notation?
3. How can you multiply numbers in scientific notation?
4. Why is scientific notation useful in mathematics?
5. What is the difference between standard form and scientific notation?

Tip: Always remember that in scientific notation, you move the decimal point until you have one non-zero digit to the left, then adjust the exponent of 10 accordingly.