Multiply the following and express the result in scientific notation. \( \left.\qquad\left(8 \times 10^{3}\right)\left(9 \times 10^{9}\right)\right] \)

To multiply the numbers in scientific notation, you first multiply the coefficients (the numbers in front) and then add the exponents. So, you multiply \(8\) and \(9\) to get \(72\). Then, you add the exponents from \(10^3\) and \(10^9\): \[ 3 + 9 = 12. \] Now, we have: \[ 72 \times 10^{12}. \] However, \(72\) is not in proper scientific notation (which requires a coefficient between \(1\) and \(10\)). To convert \(72\) into scientific notation, you can write it as \(7.2 \times 10^1\). Now, combine: \[ 7.2 \times 10^1 \times 10^{12} = 7.2 \times 10^{1 + 12} = 7.2 \times 10^{13}. \] So, the final result is \(7.2 \times 10^{13}\).