10^123 = 2^x
find x
\(\begin{array}{|rcll|} \hline 10^{123} &=& 2^x \quad & | \quad \log_{10}() \\ \log_{10}(10^{123}) &=& \log_{10}(2^x) \\ 123\cdot \log_{10}(10) &=& x\cdot \log_{10}(2) \quad & | \quad \log_{10}(10) = 1 \\ 123 &=& x\cdot \log_{10}(2) \\ x\cdot \log_{10}(2) &=& 123 \\ x &=& \frac{123}{\log_{10}(2)} \\ x &=& \frac{123}{0.30102999566} \\ \mathbf{x} & \mathbf{=} & \mathbf{408.597155671} \\ \hline \end{array}\)