The expression to calculate is:

$(3 \times 10^{-6}) \times (3 \times 10^{-13})$

To simplify this:

1. Multiply the constants: $3 \times 3 = 9$

2. Add the exponents of 10 (using the property of exponents $10^a \times 10^b = 10^{a+b}$): $-6 + (-13) = -19$

Therefore, the expression becomes:

$9 \times 10^{-19}$

In standard form, the answer is:

$9 \times 10^{-19}$

Would you like further details or have any questions?

Here are some related questions:

1. How do you multiply numbers in scientific notation?
2. What are the rules for adding exponents?
3. What is standard form in mathematics?
4. How do you handle negative exponents?
5. How can you simplify expressions with powers of 10?

Tip: When multiplying numbers in scientific notation, remember to multiply the coefficients and add the exponents.