Chapter 4 - Inverse, Exponential, and Logarithmic Functions - 4.4 Evaluation Logarithms and the Change-of-Base Theorem - 4.4 Exercises - Page 456: 19

$\approx 3.9494$

Apply logarithmic property : $\log (mn)=\log m+\log n$ Re-write as: $\log (387 \times 23)=\log 387+\log 27$ Now, take logarithmic to the base $10$ and evaluate the result. Therefore, our answer is: $\log_{10} (387 \times 23)=\log_{10} 387+\log_{10} 27 \approx 3.9494$